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Flower

Flower

:This article is about the plants; for other uses see Flower (disambiguation). Flower (disambiguation) Flower (Latin flos, floris; French fleur), a term popularly used for the bloom or blossom of a plant, is the reproductive structure of those plants classified as angiosperms (flowering plants; Division Magnoliophyta). The flower structure incorporates the reproductive organs, and its function is to produce seeds through sexual reproduction. For the higher plants, seeds are the next generation, and serve as the primary means by which individuals of a species are dispersed across the landscape. After fertilization, portions of the flower develop into a fruit containing the seed(s).

Flower anatomy

Flowering plants are heterosporangiate (producing two types of reproductive spores) and the pollen (male spores) and ovules (female spores) are produced in different organs, but these are together in a bisporangiate strobilus that is the typical flower. A flower is regarded as a modified stem (Eames, 1961) with shortened internodes and bearing, at its nodes, structures that may be highly modified leaves. In essence, a flower structure forms on a modified shoot or axis with an apical meristem that does not grow continuously (growth is determinate). The stem is called a pedicel, the end of which is the torus or receptacle. The parts of a flower are arranged in whorls on the torus. The four main parts or whorls (starting from the base of the flower or lowest node and working upwards) are as follows: flower
- calyx – the outer whorl of sepals; typically these are green, but are petal-like in some species.
- corolla – the whorl of petals, which are usually thin, soft and colored to attract insects that help the process of pollination.
- androecium (from Greek andros oikia: man's house) – one or two whorls of stamens, each a filament topped by an anther where pollen is produced. Pollen contains the male gametes.
- gynoecium (from Greek gynaikos oikia: woman's house) – one or more pistils. The female reproductive organ is the carpel: this contains an ovary with ovules (female gametes). A pistil may consist of a number of carpels merged together, in which case there is only one pistil to each flower, or of a single individual carpel (the flower is then called apocarpous). The sticky tip of the pistil, the stigma, is the receptor of pollen. The supportive stalk, the style becomes the pathway for pollen tubes to grow from pollen grains adhering to the stigma, to the ovules, carrying the reproductive material. carpel Although the floral structure described above is considered the "typical" structural plan, plant species show a wide variety of modifications from this plan. These modifications have significance in the evolution of flowering plants and are used extensively by botanists to establish relationships among plant species. For example, the two subclasses of flowering plants may be distinguished by the number of floral organs in each whorl: dicotyledons typically having 4 or 5 organs (or a multiple of 4 or 5) in each whorl and monocotyledons having three or some multiple of three. The number of carpels in a compound pistil may be only two, or otherwise not related to the above generalization for monocots and dicots. In the majority of species, individual flowers have both pistils and stamens as described above. These flowers are described by botanists as being perfect, bisexual, or hermaphrodite. However, in some species of plants the flowers are imperfect or unisexual: having only either male (stamens) or female (pistil) parts. In the latter case, if an individual plant is either male or female the species is regarded as dioecious. However, where unisexual male and female flowers appear on the same plant, the species is considered monoecious. Some flowers with both stamens and a pistil are capable of self-fertilization, which does increase the chance of producing seeds but limits genetic variation. The extreme case of self-fertilization occurs in flowers that always self-fertilize, such as the common dandelion. Conversely, many species of plants have ways of preventing self-fertilization. Unisexual male and female flowers on the same plant may not appear at the same time, or pollen from the same plant may be incapable of fertilizing its ovules. The latter flower types, which have chemical barriers to their own pollen, are referred to as self-sterile or self-incompatible. (See also: Plant sexuality) Plant sexuality Additional discussions on floral modifications from the basic plan are presented in the articles on each of the basic parts of the flower. In those species that have more than one flower on an axis, the collection of flowers is termed an inflorescence. In this sense, care must be exercised in considering what is a flower. In botanical terminology, a single daisy or sunflower for example, is not a flower but a flower head—an inflorescence comprised of numerous small flowers (sometimes called florets). Each small flower may be anatomically as described above.

Floral formula

A floral formula is a way to represent the structure of a flower using specific letters, numbers, and symbols. Typically, a general formula will be used to represent the flower structure of a plant family rather than a particular species. The following representations are used: Ca = calyx (sepal whorl; e.g. Ca⁵ = 5 sepals)
Co = corolla (petal whorl; e.g., Co^3(x) = petals some multiple of three )
Z = add if zygomorphic (e.g., CoZ⁶ = zygomorphic with 6 petals)
A = androecium (whorl of stamens; e.g., A^∞ = many stamens)
G = gynoecium (carpel or carpels; e.g., G¹ = monocarpous)
x - to represent a "variable number"
∞ - to represent "many"
A floral formula would appear something like this: Ca⁵Co⁵A^{10 - ∞}G¹ Several other symbols are used that will have to await drawings to illustrate here (see [http://botit.botany.wisc.edu/courses/systematics/key.html]).

Flower function

family] The function of a flower is to mediate the union of male and female gametes. The process is termed pollination. Many flowers are dependent upon the wind to move pollen between flowers of the same species. Others rely on animals (especially insects) to accomplish this feat. The period of time during which this process can take place (the flower is fully expanded and functional) is called anthesis. Many flowers in nature have evolved to attract animals to pollinate the flower, the movements of the pollinating agent contributing to the opportunity for genetic recombinations within a dispersed plant population. Flowers that are insect pollinated are called entomophilous (literally "insect loving"). Flowers commonly have nectaries on their various parts that attract these animals. Bees and birds are common pollinators: both have color vision, thus selecting for "colorful" flowers. Some flowers have patterns, called nectar guides, that are evident in the ultraviolet range, visible to bees but not to humans. Flowers also attract pollinators by scent. In any case, pollinators are attracted to the plant, perhaps in search of nectar, which they eat. The arrangement of the stamens ensures that pollen grains are transferred to the bodies of the pollinator. In gathering nectar from many flowers of the same species, the pollinators transfer pollen between all of the flowers it visits. Flower scent is not always pleasant to our sense of smell. Some plants, such as Rafflesia, the titan arum, and the North American pawpaw (Asimina triloba) are pollinated by flies, so produce a scent imitating rotting meat. Other flowers are pollinated by the wind, and the flowers of these species (for example, grasses) have no need to attract pollinators and therefore tend not to be "showy". Wind pollinated flowers are referred to as anemophilous. Whereas the pollen of entomophilous flowers tends to be large grained, sticky, and contain significant protein (another "reward" for pollinators), Anemophilous flower pollen is usually small grained, very light, and of little nutritional value to insects, though it may still be gathered, in times of dearth. Honeybees and bumblebees actively gather anemophilous corn (maize) pollen, though it is of little value to them. There is much confusion about the role of flowers in allergies. For example the showy and entomophilous goldenrod (Solidago) is frequently blamed for respiratory allergies, of which it is innocent, since its pollen cannot be airborne. Instead the allergen is usually the pollen of the contemporary bloom of anemophilous ragweed (Ambrosia) which can drift for many kilometers.

Flowers in gardening and horticulture

Main and related articles at: Gardening, Horticulture, List of flowers, and Flower album Flower album

Flowers in the arts

The great variety of delicate and beautiful flowers has inspired the works of many poets, especially from the Romantic era. Famous examples include William Blake's Ah! Sun-Flower and William Wordsworth's I Wandered Lonely as a Cloud. Ah, Sun-flower weary of time,
Who countest the steps of the Sun,
Seeking after that sweet golden clime
Where the traveller's journey is done:

Where the Youth pined away with desire,
And the pale Virgin shrouded in snow
Arise from their graves, and aspire
Where my Sun-flower wishes to go. :– William Blake, Ah! Sun-Flower The Roman goddess of flowers, gardens, and the season of Spring is Flora. The Greek goddess of spring, flowers and nature is Chloris.

Flowers in everyday life

In modern times, people have sought ways to cultivate, buy, wear, or just be around flowers and blooming plants, partly because of their agreeable smell. Around the world, florists sell flowers for a wide range of events and functions that, cumulatively, encompass one's lifetime:
- For new births or Christenings
- As a corsage or boutonniere to be worn at social functions or for holidays
- For wedding flowers for the bridal party, and decorations for the hall
- As brightening decorations within the home
- As a gift of remembrance for bon voyage parties, welcome home parties, and "thinking of you" gifts
- For funeral flowers and flowers for the grieving Florists depend on an entire network of commercial growers and shippers to support this trade. To get flowers that are out of season in their country, florists contact wholesalers who have direct connections with growers in other countries to provide those flowers.

Flowers as symbols

Many flowers have important symbolic meanings in Western culture. The practice of assigning meanings to flowers is known as floriography. Some of the more common examples include:
- Red roses are given as a symbol of love, beauty, and passion.
- Poppies are a symbol of consolation in time of death. In the UK, Australia and Canada, red poppies are worn to commemorate soldiers who have died in times of war.
- Irises are a symbol of death.
- Daisies are a symbol of innocence. Flowers within art are also representative of the female genitalia, as seen in the works of artists such as Georgia O'Keefe, Imogene Cunningham, and Judy Chicago.

References

- Eames, A. J. 1961. Morphology of the Angiosperms. McGraw-Hill Book Co., New York.

External links

- [http://la.essortment.com/floweranatomy_raxw.htm Flower Anatomy]
- [http://www.flowercouncil.org Flower Council of Holland].
- [http://www.lovetoknow.com/Flowers/flowers.htm Flower Encyclopedia]
- [http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/F/Flowering.html Flowering] in [http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/ Kimball's Biology Pages]
- [http://www.mystiqueflowers.org Flowers] Flower Types & Meanings
- [http://landscaping.about.com/od/galleryoflandscapephotos/a/flower_pictures.htm Flower Pictures]
- [http://www.flower-arrangement.org Flower Arrangement]
- [http://house-flowers.com House Flowers Council].
- [http://eir.library.utoronto.ca/rpo/display/poem160.html William Blake: Ah Sun-Flower]
- [http://develop.consumerium.org/wiki/index.php/Flowers Flowers] at the Development Wiki of Consumerium Project
- [http://www.lib.ksu.edu/wildflower/drawing/simpleflower.jpg flower schematic]
- [http://www.flowerism.com Flowerism]An artist's devotion to painting of flowers
- [http://800florals.com/care/glossary.asp Glossary of Flowers] - Pictures and Names ---- A flower in a cryptic crossword could be pronounced flo-er and refer to a stream or river.
- Category:Plant anatomy Category: plant morphology Category:Reproductive system zh-min-nan:Hoe ko:꽃 ja:花 simple:Flower th:ดอกไม้

Flower (disambiguation)

Flower can mean several things:
- Flower, a structure found in plants
- Flower class corvette, a class of ships in World War II
- Flowers is an album by Ace of Base

Latin

Latin is an ancient Indo-European language originally spoken in the region around Rome called Latium. It gained great importance as the formal language of the Roman Empire. All Romance languages, those being most notably Spanish, French, Portuguese, Italian, and Romanian, are descended from Latin, and many words based on Latin are found in other modern languages such as English. The Latin alphabet, derived from the Greek, remains the most widely-used alphabet in the world. It is said that 80 percent of scholarly English words are derived from Latin (in a large number of cases by way of French). Moreover, in the Western world, Latin was a lingua franca, the learned language for scientific and political affairs, for more than a thousand years, being eventually replaced by French in the 18th century and English in the late 19th. Ecclesiastical Latin remains the formal language of the Roman Catholic Church to this day, and thus the official national language of the Vatican. The Church used Latin as its primary liturgical language until the Second Vatican Council in the 1960s. Latin is also still used (drawing heavily on Greek roots) to furnish the names used in the scientific classification of living things. The modern study of Latin, along with Greek, is known as Classics.

Main features

Latin is a synthetic inflectional language: affixes (which usually encode more than one grammatical category) are attached to fixed stems to express gender, number, and case in adjectives, nouns, and pronouns, which is called declension; and person, number, tense, voice, mood, and aspect in verbs, which is called conjugation. There are five declensions (declinationes) of nouns and four conjugations of verbs. There are six noun cases: #nominative (used as the subject of the verb or the predicate nominative), #genitive (used to indicate relation or possession, often represented by the English of or the addition of s to a noun), #dative (used of the indirect object of the verb, often represented by the English to or for), #accusative (used of the direct object of the verb, or object of the preposition in some cases), #ablative (separation, source, cause, or instrument, often represented by the English by, with, from), #vocative (used of the person or thing being addressed). In addition, some nouns have a locative case used to express location (otherwise expressed by the ablative with a preposition such as in), but this survival from Proto-Indo-European is found only in the names of lakes, cities, towns, small islands, and a few other words related to locations, such as "house", "ground", and "countryside". Latin itself, being a very old language, is far closer to Proto-Indo-European than are most modern Western European languages; it has, in fact, about the same relationship with PIE as modern Italian or French has to Latin. There are six general tenses in Latin (technically they are tense/aspect/mood complexes). The indicative mood can be used with all of them. The subjunctive mood, however, has only present, imperfect, perfect, and pluperfect tenses. These tenses in the subjunctive mood do not completely correlate in meaning to the tenses in the indicative. The following examples are of the first conjugation verb "laudare" ("to praise") in the indicative mood and the active voice:
Primary sequence tenses
# present (laudo, "I praise") # imperfect (laudabam, "I was praising") # future (laudabo, "I shall praise," "I will praise")
Secondary sequence tenses
# perfect (laudavi, "I praised", "I have praised") # pluperfect (laudaveram, "I had praised") # future perfect (laudavero, "I shall have praised," "I will have praised") The future perfect tense can also imply a normal future idea (like in "When I will have run...") and so may also sometimes be included in the primary sequence.
Latin and Romance
After the collapse of the Roman Empire, Latin evolved into the various Romance languages. These were for many centuries only spoken languages, Latin still being used for writing. For example, Latin was the official language of Portugal until 1296 when it was replaced by Portuguese. The Romance languages evolved from Vulgar Latin, the spoken language of common usage, which in turn evolved from an older speech which also produced the formal classical standard. Latin and Romance differ (for example) in that Romance had distinctive stress, whereas Latin had distinctive length of vowels. In Italian and Sardo logudorese, there is distinctive length of consonants and stress, in Spanish only distinctive stress, and in French even stress is no longer distinctive. Another major distinction between Romance and Latin is that all Romance languages, excluding Romanian, have lost their case endings in most words except for some pronouns. Romanian retains a direct case (nominative/accusative), an indirect case (dative/genitive), and vocative. In Italy, Latin is still compulsory in secondary schools as Liceo Classico and Liceo Scientifico which are usually attended by people who aim to the highest level of education. In Liceo Classico Ancient Greek is a compulsory subject.
Latin and English
See Latin influence in English for a more complete exposition. English grammar is independent of Latin grammar, though prescriptive grammarians in English have been heavily influenced by Latin. Attempts to make English grammar follow Latin rules — such as the prohibition against the split infinitive — have not worked successfully in regular usage. However, as many as half the words in English were derived from Latin, including many words of Greek origin first adopted by the Romans, not to mention the thousands of French, hundreds of Spanish, Portuguese and Italian words of Latin origin that have also enriched English. During the 16th and on through the 18th century English writers created huge numbers of new words from Latin and Greek roots. These words were dubbed "inkhorn" or "inkpot" words (as if they had spilled from a pot of ink). Many of these words were used once by the author and then forgotten, but some remain. Imbibe, extrapolate, dormant and inebriation are all inkhorn terms carved from Latin words. In fact, the word etymology is derived from the Greek word etymologia, meaning "true sense of the word." Latin was once taught in many of the schools in Britain with academic leanings - perhaps 25% of the total [http://www.channel4.com/history/microsites/T/teachem2/thennow/]. However, the requirement for it was gradually abandoned in the professions such as the law and medicine, and then, from around the late 1960s, for admission to university. After the introduction of the Modern Language GCSE in the 1980s, it was gradually replaced by other languages, although it is now being taught by more schools along with other classical languages.
Latin education
The linguistic element of Latin courses offered in high schools or secondary schools, and in universities, is primarily geared toward an ability to translate Latin texts into modern languages, rather than using it in oral communication. As such, the skill of reading is heavily emphasized, whereas speaking and listening skills are barely touched upon. However, there is a growing movement, sometimes known as the Living Latin movement, whose supporters believe that Latin can, or should, be taught in the same way that modern "living" languages are taught, that is, as a means of both spoken and written communication. One of the most interesting aspects of such an approach is that it assists speculative insight into how many of the ancient authors spoke and incorporated sounds of the language stylistically; without understanding how the language is meant to be heard it is very difficult to identify patterns in Latin poetry. Institutions offering Living Latin instruction include the Vatican and the University of Kentucky. In Britain the Classical Association encourages this approach, and there has been something of a vogue for books describing the adventures of a mouse called Minimus. In the United States there is a thriving competitive organization for high school Latin students, the National Junior Classical League (the second-largest youth organization in the world after the Boy Scouts), backed up by the Senior Classical League for college students. Many would-be international auxiliary languages have been heavily influenced by Latin, and the moderately successful Interlingua considers itself to be the modernized and simplified version of the language (le latino moderne international e simplificate). Latin translations of modern literature such as Paddington Bear, Winnie the Pooh, Harry Potter and the Philosopher's Stone, Le Petit Prince, Max und Moritz, and The Cat in the Hat have also helped boost interest in the language.
See also

About the Latin language

- Latin grammar
- Latin spelling and pronunciation
- Latin declension
- Latin conjugation
- Latin alphabet
- List of Latin words with English derivatives
- Latin verbs with English derivatives
- Latin nouns with English derivatives
- ablative absolute
- Word order in Latin
About the Latin literary heritage

- Latin literature
- Romance languages
- Loeb Classical Library
- List of Latin phrases
- List of Latin proverbs
- Brocard
- List of Latin and Greek words commonly used in systematic names
- List of Latin place names in Europe
- Carmen Possum
Other related topics

- Roman Empire
- Internationalism
References

- Bennett, Charles E. Latin Grammar (Allyn and Bacon, Chicago, 1908)
- N. Vincent: "Latin", in The Romance Languages, M. Harris and N. Vincent, eds., (Oxford Univ. Press. 1990), ISBN 0195208293
- Waquet, Françoise, Latin, or the Empire of a Sign: From the Sixteenth to the Twentieth Centuries (Verso, 2003) ISBN 1859844022; translated from the French by John Howe.
- Wheelock, Frederic. Latin: An Introduction (Collins, 6th ed., 2005) ISBN 0060784237
External links

- [http://www.jambell.com/latin.html Latin Phrases for after dinner conversation (Thanks to Elaine Poole)]
- [http://www.ethnologue.com/show_language.asp?code=lat Ethnologue report for Latin]
- [http://forumromanum.org/literature/index.html Corpus Scriptorum Latinorum] is a comprehensive webography of Latin texts and their translations.
- [http://www.perseus.tufts.edu/ The Perseus Project] has many useful pages for the study of classical languages and literatures, including [http://www.perseus.tufts.edu/cgi-bin/resolveform?lang=Latin an interactive Latin dictionary].
- [http://lysy2.archives.nd.edu/cgi-bin/words.exe words by William whitaker] is a dictionary program online capable of looking up various word forms.
- [http://retiarius.org/ Retiarius.Org] includes a Latin text search engine.
- [http://www.nd.edu/~archives/latgramm.htm Latin-English dictionary and Latin grammar from U of Notre Dame]
- [http://latin-language.co.uk/ Latin language] History of Latin language, Latin texts with English translation and a collection of dictionaries.
- [http://augustinus.eresmas.net/scl/ Societas Circulorum Latinorum] gathers together Latin Circles all over the world.
- [http://www.learnlatin.tk LearnLatin.tk] - Free online course in Latin
- [http://www.latintests.net/ LatinTests.net] - Lets Latin learners test their grammar and vocabulary with self-checking quizzes.
- [http://thelatinlibrary.com/ The Latin Library] contains many Latin etexts
- [http://www.textkit.com/ Textkit] has Latin textbooks and etexts.
- [http://www.websters-online-dictionary.org/definition/Latin-english/ Latin–English Dictionary]: from Webster's Rosetta Edition.
- [http://www.language-reference.com/ Language reference] Cross-foreign-language lexicon powered by its own search engine. All cross combinations between Latin and French, German, Italian, Spanish.
- [http://comp.uark.edu/~mreynold/rhetor.html Rhetor by Gabriel Harvey] was originally published in 1577 and never again reprinted.
- [http://freewebs.com/omniamundamundis omniamundamundis] Latin hypertexts from fourteen ancient Roman authors.
- [http://www.saltspring.com/capewest/pron.htm Pronunciation of Biological Latin, Including Taxonomic Names of Plants and Animals]
- [http://www.yleradio1.fi/nuntii Nuntii Latini (News in Latin)], written and spoken (RealAudio) news in latin. Weekly review of world news in Classical Latin, the only international broadcast of its kind in the world, produced by YLE, the Finnish Broadcasting Company.
- [http://www.tranexp.com:2000/InterTran?url=http%3A%2F%2F&type=text&text=Replace%20Me&from=eng&to=ltt InterTran Latin], Translate from Latin to ENGLISH or vice versa.
- [http://www.latinvulgate.com Latin Vulgate] The Latin and English of the Old & New Testaments in parallel, along with the Complete Sayings of Jesus in parallel Latin and English. Category:Classical languages Category:Ancient languages Category:Fusional languages Category:Languages of Italy Category:Languages of Vatican City als:Latein zh-min-nan:Latin-gí ko:라틴어 ja:ラテン語 simple:Latin language th:ภาษาละติน

French language

French (French: français) is the third of the Romance languages in terms of number of speakers, after Spanish and Portuguese, being spoken by about 67 million people as a mother tongue, and altogether by some 128 million people, which includes second-language speakers who use French for daily communication. French is thus the 18^th most spoken language in the world by number of native speakers, and 9^th in terms of daily speakers. It is an official language in 29 countries. It is also an official or administrative language in various communities and organisations (such as the European Union, IOC, United Nations and Universal Postal Union). Before World War II, French was considered the international language, particularly in such fields as diplomacy, trade, shipping, and transportation.

History

The Roman invasion of Gaul

The French language is a Romance language, meaning that it is descended from Latin. Before the Roman invasion of what is modern-day France by Julius Cæsar (58–52 BC), France was inhabited largely by a Celtic people that the Romans referred to as Gauls, although there were also other linguistic/ethnic groups in France at this time, such as the Iberians in southern France and Spain, the Ligurians on the Mediterranean coast, Greek colonies such as Massalia (i.e. present-day Marseille), Phoenician outposts, and the Vascons on the Spanish/French border. Although in the past many Frenchmen liked to refer to their descent from Gallic ancestors (nos ancêtres les Gaulois), perhaps fewer than 200 words with a Celtic etymological origin remain in French today (largely place and plant names and words dealing with rural life and the earth). In the reverse direction, some words for Gallic objects which were new to the Romans and for which there were no words in Latin were imported into Latin – for example, clothing items such as les braies. Latin quickly became the lingua franca of the entire Gallic region for mercantile, official and educational purposes, yet it should be remembered that this was Vulgar Latin, the colloquial dialect spoken by the Roman army and its agents and not the literary dialect of Cicero.

The Franks

From the third century on, Western Europe was invaded by Germanic tribes from the east, and some of these groups settled in Gaul. For the history of the French language, the most important of these groups are the Franks in northern France, the Alemanni in the German/French border, the Burgundians in the Rhone valley and the Visigoths in the Aquitaine region and Spain. These Germanic-speaking groups had a profound effect on the Latin spoken in their respective regions, altering both the pronunciation and the syntax. They also introduced a number of new words: perhaps as much as 15% of modern French comes from Germanic words, including many terms and expressions associated with their social structure and military tactics.

Langue d'Oïl

Linguists typically divide the languages spoken in medieval France into three geographical subgroups: Langue d'oïl and Langue d'oc are the two major groups; the third group, Franco-Provençal, is considered a transitional language between the two other groups. The Oïl–Oc divide is broadly comparable to the divide illustrated by the use of "yes" in English and "aye" in Scots. Langue d'oïl, the languages which use oïl (in modern usage, oui) for "yes", is the language group in the north of France. These languages, like Picard, Walloon, Francien and Norman, were influenced by the Germanic languages spoken by the Frankish invaders. From the time period Clovis I on, the Franks extended their rule over northern Gaul. Over time, the French language developed from either the Oïl language found around Paris (the Francien theory) or from a standard administrative language based on common characteristics found in all Oïl languages (the lingua franca theory). Langue d'oc, the languages which use oc for "yes", is the language group in the south of France and northern Spain. These languages, such as Gascon and Provençal, have relatively little Frankish influence. (Modern French has two words for "yes", oui and si; the latter is used to contradict negative statements. Si derives from Latin sic "thus", and is cognate to the word for "yes" in Spanish, Italian, and Catalan. Oïl/oui derive, according to Larousse, from Latin hoc ille "thus he (did)".)

Other linguistic groups

The early middle ages also saw the influence of other linguistic groups on the dialects of France: From the 5th to the 8th centuries, Celtic-speaking peoples from southwestern Britain (Wales, Cornwall, Devon) travelled across the English Channel, both for reasons of trade and as a result of the Anglo-Saxon invasions of England. They established themselves in Bretagne (Brittany). Their language was a dialect of the Brythonic languages, which has been named Breton in more recent centuries. It is part of the larger Celtic language family, though the modern dialects reflect a noticeable influence from French in their vocabulary. From the 6th to the 7th centuries, the Vascons crossed over the Pyrénées, a mountain range in the south of France. Their presence influenced the Occitan language spoken in southwestern France, resulting in the dialect called Gascon. Scandinavian vikings invaded France from the 9th century onwards and established themselves in what would come to be called Normandie (Normandy). They took up the langue d'oïl spoken there and contributed many words to French related to maritime activities, amongst other things. With their conquest of England in 1066, the Normans brought their language. The dialect that developed there as a language of administration and literature is referred to as Anglo-Norman. Anglo-Norman served as the language of the ruling classes and commerce in England from the time of the conquest until 1362, when the use of English became dominant again. Because of the Norman Conquest, the English language has borrowed a considerable amount of its vocabulary from French. The Arab peoples also supplied many words to French around this time period, including words for luxury goods, spices, trade stuffs, sciences and mathematics.

History of French

For the period up to around 1300, some linguists refer to the oïl languages collectively as Old French (ancien français). The earliest extant text in French is the Oaths of Strasbourg from 842; Old French became a literary language with the chansons de geste that told tales of the paladins of Charlemagne and the heroes of the Crusades. By the Ordinance of Villers-Cotterêts in 1539 King Francis I made French the official language of administration and court proceedings in France, ousting the Latin that had been used before then. With the imposition of a standardised chancery dialect and the loss of the declension system, the dialect is referred to as Middle French (moyen français). Following a period of unification, regulation and purification, the French of the 17th to the 18th centuries is sometimes referred to as Classical French (français classique), although many linguists simply refer to French language from the 17th century to today as Modern French (français moderne). The foundation of the Académie française (French Academy) in 1634 by Cardinal Richelieu created an official body whose goal has been the purification and preservation of the French language. This group of 40 members is known as the Immortals, not, as some erroneously believe, because they are chosen to serve for the extent of their lives (which they are), but because of the inscription engraved on the official seal given to them by their founder Richelieu—"À l'immortalité" ("to the Immortality (of the French language)"). The foundation still exists and contributes to the policing of the language and the adaptation of foreign words and expressions. Some recent modifications include the change from software to logiciel, packet-boat to paquebot, and riding-coat to redingote. The word ordinateur for computer was however not created by the Académie, but by a linguist appointed by IBM (see :fr:ordinateur). From the 17th to the 19th centuries, France was the leading power of continental Europe; thanks to this, together with the influence of the Enlightenment, French was the lingua franca of educated Europe, especially with regards to the arts, literature, and diplomacy; monarchs like Frederick II of Prussia and Catherine the Great of Russia could both speak and write in French. Through the Académie, public education, centuries of official control and the role of media, a unified official French language has been forged, but there remains a great deal of diversity today in terms of regional accents and words. For some critics, the "best" pronunciation of the French language is considered to be the one used in Touraine (around Tours and the Loire River valley), but such value judgments are fraught with problems, and with the ever increasing loss of lifelong attachments to a specific region and the growing importance of the national media, the future of specific "regional" accents is difficult to predict.

Modern issues

There is some debate in today's France about the preservation of the French language and the influence of English (see franglais), especially with regard to international business, the sciences and popular culture. There have been laws (see Toubon law) enacted which require that all print ads and billboards with foreign expressions include a French translation and which require quotas of French-language songs (at least 40%) on the radio. There is also pressure, in differing degrees, from some regions as well as minority political or cultural groups for a measure of recognition and support for their regional languages.

Geographic distribution

regional language
French is an official language in the following countries or parts thereof: La Francophonie is an international organization of French-speaking countries and governments.

Legal status in France

Per the Constitution of France, French is the official language of the Republic since 1792 [http://www.languefrancaise.net/dossiers/dossiers.php?id_dossier=50]. France mandates the use of French in official government publications, public education outside of specific cases (though these dispositions are often ignored) and legal contracts; advertisements must bear a translation of foreign words. See Toubon Law. Contrary to a misunderstanding common in the American and British media, France does not prohibit the use of foreign words in websites or any other private publication, which would anyway contradict constitutional guarantees on freedom of speech. The misunderstanding may have arisen from a similar prohibition in the Canadian province of Quebec which made strict application of the Charter of the French Language between 1977 and 1993, although these regulations addressed language used in advertising and the provision of commercial services offered within the province, not the language of private communication. There exist in addition to French a variety of languages spoken in France by minorities; see Languages of France.

Legal status in Canada

About 12% of the world's francophones are Canadian, and French is one of Canada's two official languages, with English; various provisions of the Canadian Charter of Rights and Freedoms deal with the right of Canadians to access services in English and French all across Canada. By law, the federal government must operate and provide services in both English and French; proceedings of the Parliament of Canada must be translated into both English and French; and all Canadian products must be labelled in both English and French. Overall about 22% of Canadians speak French as a first language and 18% are bilingual. French has been the only official language of Quebec since 1974, although it is commonly (and incorrectly) believed that the designation of French as the sole official language occurred in 1977 with the adoption of the Charter of the French Language (which is popularly referred to as Bill 101). By far the provision of Bill 101 with the most significant impact has been that which mandates French-language education, unless a child's parents or siblings have received the major part of their own education in English within Canada. That provision has reversed a historical trend whereby a large number of immigrant children were being sent to English schools by their parents. In so doing, Bill 101 has greatly contributed to the "visage français" (French face) of Quebec. Other provisions of Bill 101, on the other hand, have been ruled unconstitutional over the years, including those mandating French-only commercial signs, court proceedings, and debates in the legislature. Some of those provisions have remained in effect, for a while, using the constitutional "notwithstanding" clause that permits a non-compliant law to temporarily remain. No "notwithstanding provision" is currently in effect. In 1993 the Charter was changed to allow signage in other languages so long as French is markedly "predominant". The Charter also provides for a measure of access by Anglophones to health and social services in their own language. The only province which has French as an official language is New Brunswick. In Ontario and Manitoba, French does not have full official status, although the provincial governments do provide full French-language services in all communities where significant numbers of francophones live. All of the other provinces do make some effort to accommodate the needs of their francophone citizens, although the level and quality of French-language service varies significantly from province to province.

Legal status in Switzerland

French is an official language in Switzerland. It is spoken in the part of Switzerland called Romandy.

Dialects of French

- Acadian French
- African French
- Belgian French
- Cajun French
- Canadian French
- Cambodian French
- Louisiana Creole French
- français d'Aoste
- français-germanique
- Indian French
- Levantine French
- Maghreb French
- Newfoundland French
- North American French
- Oceanic French
- Quebec French
- South East Asian French
- Swiss French
- West Indian French
- [http://www.linguasphere.org/langues_romanes.pdf linguasphere on Romance languages]

Languages derived from French

- Antillean Creole
- Haitian Creole
- Lanc-Patuá
- Mauritian Creole
- Michif
- Louisiana Creole French
- Réunionese Creole
- Seychellois Creole
- Tay Boi

Sounds

:Main article: French phonology and orthography French pronunciation follows strict rules based on spelling, but French spelling is often based more on history than phonology. The rules for pronunciation vary between dialects, but the standard rules are:
- liaison or linking: Final single consonants, in particular s, x, z, t, d, n and m, are normally silent. (The final letters 'c', 'r', 'f', and 'l' however are normally pronounced.) When the following word begins with a vowel, though, a silent consonant may once again be pronounced, to provide a "link" between the two words and avoid a glottal stop between them. Some liaisons are mandatory, for example the s in les amants or vous avez; some are optional, depending on dialect and register, for example the first s in deux cents euros or euros irlandais; and some are forbidden, for example the s in beaucoup d'hommes aiment. The t of et is never pronounced and the silent final consonant of a noun is only pronounced in the plural and in set phrases like pied-à-terre. Doubling a final consonant and adding a silent e at the end of a word (e.g. Parisien → Parisienne) makes it clearly pronounced, always.
- elision or vowel dropping: Monosyllabic words such as je or que drop their final vowel before another word beginning with a vowel. The missing vowel is replaced by an apostrophe. (e.g. je ai is instead pronounced and spelt → j'ai)
- nasal "n" and "m". When "n" or "m" follows a vowel combination, the "n" and "m" become silent and cause the preceding vowel to become nasalized (i.e. pronounced with the soft palate extended downward so as to allow part of the air to leave through the nostrils). Exceptions are when the "n" or "m" is doubled, or immediately followed by a vowel. The prefixes en- and em- are always nasalized. The rules get more complex than this but may vary between dialects.
- digraphs French does not introduce extra letters or diacritics to specify its large range of vowel sounds and diphthongs, rather it uses specific combinations of vowels, sometimes with following consonants, to show which sound is intended. (See French phonology and orthography or [http://www.languageguide.org/francais/grammar/pronunciation/ French Pronunciation Guide] for more details.)
- accents are used sometimes for pronunciation, sometimes to distinguish similar words, and sometimes for etymology alone.
- Accents that affect pronunciation:
- "é", is pronounced instead of the defaults or,
- "è" (e.g., secrète) means that the vowel is pronounced (as usual),
- dieresis (e.g. naïve, Noël) as in English, specifies that this vowel is pronounced separately from the preceding one (or following one in some cases), not combined,
- the "ç" means that the letter c is pronounced in front of A, O, or U. ("c" is otherwise hard before a hard vowel.)
- The circumflex (e.g. pâté, forêt) shows that an e is pronounced and that an o is pronounced . In some dialects it also signifies a pronunciation of for the letter a, but this differentiation is disappearing. It usually indicates a former long vowel created by the dropping of an "s" from the Latin root (as in English "paste", "forest"),
- Accents with no pronunciation effect:
- The circumflex does not affect the pronunciation of the letters i or u, and in most dialects, a as well.
- All other accents are used only to distinguish similar words or for etymological reasons, as in the case of distinguishing the adverbs là and où ("there", "where") from the article la and the conjunction ou ("the fem. sing.", "or") respectively.

Grammar

:Main article: French grammar French grammar shares several notable features with most other Romance languages, including:
- the loss of Latin's declensions
- only two grammatical genders
- the development of grammatical articles from Latin demonstratives
- new tenses formed from auxiliaries French word order is Subject Verb Object, except when the object is a pronoun, in which case the word order is Subject Object Verb.

Vocabulary

Word origins

The majority of French words derive from vernacular or "vulgar" Latin or were constructed from Latin or Greek roots. There are often pairs of words, one form being popular (noun) and the other one savant (adjective), both originating from Latin. Example:
- brother: frère (brother) / fraternel
- finger: doigt / digital
- faith: foi (faith) / fidèle
- cold: froid / frigide
- eye: œil / oculaire The French words which have developed from Latin are usually less recognisable than Italian words of Latin origin because as French developed into a separate language from Vulgar Latin, the unstressed final syllable of many words was dropped or elided into the following word. It is estimated that 12 percent (4,200) of common French words found in a typical dictionary such as the Petit Larousse or Micro-Robert Plus (35,000 words) are of foreign origin. About 25 percent (1,054) of these foreign words come from English and are fairly recent borrowings. The others are some 707 words from Italian, 550 from ancient Germanic languages, 481 from ancient Gallo-Romance languages, 215 from Arabic, 164 from German, 160 from Celtic languages, 159 from Spanish, 153 from Dutch, 112 from Persian and Sanskrit, 101 from Native American languages, 89 from other Asian languages, 56 from Afro-Asiatic languages, 55 from Slavic languages and Baltic languages, and 144 from other languages (3 percent of the total). Source: Henriette Walter, Gérard Walter, Dictionnaire des mots d'origine étrangère, 1998.

Levels of register

French, like many other languages, possesses a continuum of several levels of register. The colloquial register is used in almost any circumstance of life, and should not be confused with slang or rude talk. Formal French is used in writing or in formal occasions (when people make official speeches or when they are interviewed on television, for instance). Some level of formality is also normally used in classrooms in France, although colloquial French is now spoken by more and more professors with their students. Colloquial French differs from formal French in terms of grammar. For instance, the negation in formal French is "ne... pas", whereas in colloquial French it is simply "... pas", such as "I don't think so", which is "Je ne crois pas" in formal French, and "Je crois pas" in colloquial French. Another example of change in grammar is the way to ask a question: by inverting verb and subject in formal French, or also by using "est-ce que", whereas in colloquial French a question is phrased exactly as an affirmation, with the voice rising in the end. E.g.: "Is he sick?" would be "Est-il malade?" or "Est-ce qu'il est malade?" in formal French, and "Il est malade?" in colloquial French. On the other hand, questions with "est-ce que" are more colloquial than using inversion. Secondly, colloquial French differs from formal French in terms of pronunciation. Some words undergo shortening, or sound change, whereas some syllables are dropped altogether. For instance, "yes" is "oui" in formal French, and becomes "ouais" in colloquial French; "I" is "je" in formal French, but becomes "j' " in colloquial French; so a sentence like "I think he'll come" is "Je pense qu'il viendra" in formal French, and "J'pense qu'i'viendra" in colloquial French. There are many instances of shortening of words, such as "teacher", which is "professeur" in formal French, but becomes "prof'" in colloquial French.

Counting system

The French counting system is partially vigesimal: twenty () is used as a base number in the names of numbers from 70-99. So for example, means 4 times 20, i.e. is the French word for 80, and (literally "sixty-fifteen") means 75. This is comparable to archaic English use of "score", as in "fourscore and seven" (87), or "threescore and ten" (70). Belgian French and Swiss French are different in this respect.

Writing system

French is written using the Latin alphabet, plus five diacritics (the circumflex accent, acute accent, grave accent, diaeresis, and cedilla) and two ligatures (æ, œ). French spelling, like English spelling, tends to preserve obsolete pronunciation rules. This is mainly due to extreme phonetic changes since the Old French period, without a corresponding change in spelling. However, some conscious changes were also made to restore Latin orthography:
- Old French doit > French doigt "finger" (Latin digitum)
- Old French pie > French pied "foot" (Latin pedem) As a result, it is nearly impossible to predict the spelling on the basis of the sound alone. Final consonants are generally silent, except when the following word begins with a vowel. For example, all of these words end in a vowel sound: nez, pied, aller, les, finit, beaux. The same words followed by a vowel, however, may sound the consonants, as they do in these examples: beaux-arts, les amis, pied-à-terre. On the other hand, a given spelling will almost always lead to a predictable sound, and the Académie française works hard to enforce and update this correspondence. In particular, a given vowel combination or diacritic predictably leads to one phoneme. The diacritics have phonetic, semantic, and etymological significance.
- grave accent (à, è, ù): Over a or u, used only to distinguish homophones: à ("to") vs. a ("has"), ou ("or") vs. où ("where"). Over an e, indicates the sound .
- acute accent (é): Over an e, indicates the sound , the ai sound in such words as English hay or neigh. It often indicates the historical deletion of a following consonant (usually an s): écouter < escouter.
- circumflex (â, ê, î, ô û): Over an e or o, indicates the sound or , respectively. Most often indicates the historical deletion of an adjacent letter (usually an s or a vowel): château < castel, fête < feste, sûr < seur, dîner < disner. By extension, it has also come to be used to distinguish homophones: du ("of the") vs. dû (past participle of devoir "to owe"; note that dû is in fact written thus because of a dropped e: deu).
- diaeresis or tréma (ë, ï, ü): Indicates that a vowel is to be pronounced separately from the preceding one: naïve, Noël. Diaeresis on ÿ only occurs in some proper names (such as l'Haÿ-les-Roses) and in modern editions of old French texts. Since the 1990 orthographic rectifications, the diaeresis in words containing guë (such as aiguë or ciguë) was moved onto the u: aigüe, cigüe. Words coming from German retain the old Umlaut if applicable but uses French pronounciation, such as capharnaüm(mess).
- cedilla (ç): Indicates that an etymological c is pronounced when it would otherwise be pronounced /k/. Thus je lance "I throw" (with c = before e), je lançai "I threw" (c would be pronounced before a without the cedilla). The ligature œ is a mandatory contraction of oe in certain words (sœur "sister" , œuvre "work [of art]" , cœur "heart" , cœlacanthe "Coelacanth" ), sometimes in words of Greek origin, spelled with an οι diphthong which became oe in Latin, pronounced in French (and other Romance languages): œsophage , œnologie . It may also appear in œu digraph (or œ alone in œil "eye"), in words that were once written with eu digraph (which could be read or , depending on the word): bœuf "ox" (Old French buef or beuf), mœurs "custom", œil "eye" , etc. In these cases, the Latin etymon must be spelled with an o where the French word has œu: bovem > bœuf, mores > mœurs, oculum > œil. Some attempts have been made to reform French spelling, but few major changes have been made over the last two centuries.

Some common phrases

- French: français ("fran-seh")
- hello: bonjour ("bon-zhoor")
- I love you.: Je t'aime. ("jhe tem")
- My name is _____: Je m'appelle _____ ("jhe-ma-pelle")
- good-bye: au revoir ("o-ruh-vwar")
- please: s'il vous plaît (Literally: if it please you) ("sill voo pleh")
- thank you: merci ("mairr-see")
- you are welcome: de rien (Literally: Of nothing) ("duh ryeh"), je vous en prie, il n'y a pas de quoi (France); bienvenue ("byeh-venuh") (Quebec)
- that one: celui-là ("su-lwee la"), colloq. ("swee la"), or celle-là (feminine) ("cell-la")
- how much?: combien? ("kom-byen")
- English: anglais ("ahng-gleh")
- yes: oui ("wee"), colloq. ouais (seldom written) ("way")
- no: non ("non")
- I am sorry: Je suis désolé(e). (add the "e" if the speaker is feminine); ("zhahn swee deh-zo-leh"), colloq. ("shswee deh-zo-leh"). Pardon ("par-dohn")
- I do not understand: Je ne comprends pas. ("zhuh nuh comprahn pa"), colloq. Je comprends pas (with dropping of "ne") ("shcomprahn pa")
- Where are the toilets?: Où sont les toilettes ? ("oo son leh twa-let")
- Cheers (toast to someone's health): Tchin ("chin"), Santé ("san-teh") or À la vôtre ("a la votr")
- Do you speak English?: Parlez-vous anglais ? ("par-leh voo ang-gleh") OR "Est-ce que vous parlez anglais?" ("voo par-leh ang-leh")
- Excuse me: Excusez-moi. ("eh-skyu-zay mwa")
- Good night: Bonne nuit ("bun nwee")
- Hi!: Salut ! ("sal-oo")
- I am tired: Je suis fatigué(e). (add the "e" if the speaker is feminine) ("jhe swee fah-tee-gay")
- Are you coming?: Venez vous ?, Est-ce que vous venez ? (or with close friends and relatives: tu viens?)
- I am thinking about it: J'y pense. ("jhee pahnss")
- I am going to the grocery store: Je vais à l'épicerie. ("jhe vay a lay-pee-ser-ee")
- We are going to school: On va à l'école. (colloquial) ("ohn va a lay-cohl")
- She is so pretty.: Elle est si jolie. ("el ay see jho-lee")
- our neighbors to the South: Nos voisins du sud ("noh vwah-zen due sued")
- Could you help me?: Pourriez-vous m'aider ? ("poo-ree-ay voo may-day")
- May I help you?: Puis-je vous aider? ("pwee-jha voo zay-day")
- It is the best of worlds: C'est le meilleur des mondes. ("say le may-yuhr day mohnd")
- Go to bed!: Va te coucher ! ("vah te coo-shay")
- I'm watching TV.: Je regarde la télé. ("jhe re-gard lah tay-lay")
- Wikipedia, the free encyclopedia: Wikipédia, l'encyclopédie libre. ("wee-kee-pay-dee-ah, lahns-ee-kloh-pay-dee lee-bruh")
- I am the state.: L'État, c'est moi. ("leh-tah seh-mwa")

External links

-
- [http://www.dicts.info/dictlist1.php?k1=33 All free French dictionaries] Collection of free French dictionaries.
- [http://www.declan-software.com/french French language learning audio software]
- [http://www.window.to/french/ Learn French online]
- [http://www.academie-francaise.fr/ Académie Française]
- [http://french.about.com/library/begin/bl_begin_vocab.htm Beginning French Vocabulary]
- [http://radio-canada.ca/education/francaismicro/ Capsules linguistiques - Radio-Canada.ca]
- [http://www.moelc.moe.edu.sg/french/ Département de Français, Ministry of Education Language Centre, Singapore]
- [http://www.ethnologue.com/show_language.asp?code=fra Ethnologue report for French]
- [http://www.sprachprofi.de.vu/english/f.htm Free online resources for learners]
- [http://www.lexilogos.com/french_language_dictionary.htm French-English : all online dictionaries]
- [http://www.jump-gate.com/languages/french/ French Language Course]
- [http://www.ielanguages.com/french.html French Language Tutorial at ielanguages.com]
- [http://www.intuxication.org/~webtypo/le_francais_facile.htm Le français facile]
- [http://portal.wikinerds.org/rapidfrench How to learn French in 10 months]
- [http://dhost.info/defu/wiki/index.php?id=French_accentuation_rules Basic tips of French accentuation]
- [http://www.languagehelpers.com/words/french/basics.html LanguageHelpers]
- [http://www.lightandmatter.com/french/ Liberté, an online first-year French textbook]
- [http://www.listenandlearn.org/learn/french/index.php Learn French by reading and listening]
- [http://www.how-to-learn-any-language.com/e/languages/french/index.html A profile of the French language]
- [http://dhost.info/defu/wiki/index.php?id=Virtual_French_Keyboard A virtual French keyboard]
- [http://linearb.co.uk:8080/memory/ Searchable French-English dictionary, with example sentences]
- [http://atilf.atilf.fr/ Le Trésor de la Langue Française informatisé] (very comprehensive)
- [http://truckspeak.monsite.wanadoo.fr Truck Drivers' French - English, English - French Dictionary]
- [http://www.loecsen.com/travel/discover_pop.php?lang=en&to_lang=3&learn-French/ Listen to useful French expressions]
- [http://www.FrenchLanguageTips.com/ Learn French Fast & Easy]
- [http://www.wordreference.com/ Wordreference.com dictionary]
- [http://www.my-french-dictionary.com/ My French Picture Dictionary] Category:French language Category:Oïl languages Category:Languages of Belgium Category:Languages of Canada Category:Languages of France Category:Languages of Luxembourg Category:Languages of Switzerland Category:Languages of French Guiana Category:Languages of Morocco Category:Languages of French Polynesia Category:Languages of Wallis and Futuna Category:Languages of New Caledonia Category:Synthetic languages Category:Guttural R als:Französische Sprache zh-min-nan:Hoat-gí ko:프랑스어 ja:フランス語 simple:French language th:ภาษาฝรั่งเศส

Plant

- Land plants (embryophytes)
- Non-vascular plants (bryophytes)
- Marchantiophyta - liverworts
- Anthocerotophyta - hornworts
- Bryophyta - mosses
- Vascular plants (tracheophytes)
- Lycopodiophyta - clubmosses
- Equisetophyta - horsetails
- Pteridophyta - "true" ferns
- Psilotophyta - whisk ferns
- Ophioglossophyta - adderstongues
- Seed plants (spermatophytes)
- †Pteridospermatophyta - seed ferns
- Pinophyta - conifers
- Cycadophyta - cycads
- Ginkgophyta - ginkgo
- Gnetophyta - gnetae
- Magnoliophyta - flowering plants Magnoliophyta Plants are a major group of living things (about 300,000 species), including familiar organisms such as trees, flowers, herbs, and ferns. Aristotle divided all living things between plants, which generally do not move or have sensory organs, and animals. In Linnaeus' system, these became the Kingdoms Vegetabilia (later Plantae) and Animalia. Since then, it has become clear that the Plantae as originally defined included several unrelated groups, and the fungi and several groups of algae were removed to new kingdoms. However, these are still often considered plants in many contexts. Indeed, any attempt to match "plant" with a single taxon is doomed to fail, because plant is a vaguely defined concept unrelated to the presumed phylogenic concepts on which modern taxonomy is based.

Embryophytes

:See main article at Embryophytes Most familiar are the multicellular land plants, called embryophytes. They include the vascular plants, plants with full systems of leaves, stems, and roots. They also include a few of their close relatives, often called bryophytes, of which mosses and liverworts are the most common. All of these plants have eukaryotic cells with cell walls composed of cellulose, and most obtain their energy through photosynthesis, using light and carbon dioxide to synthesize food. About three hundred plant species do not photosynthesize but are parasites on other species of photosynthetic plants. Plants are distinguished from green algae, from which they evolved, by having specialized reproductive organs protected by non-reproductive tissues. Bryophytes first appeared during the early Palaeozoic. They can only survive where moisture is available for significant periods, although some species are desiccation tolerant. Most species of bryophyte remain small throughout their life-cycle. This involves an alternation between two generations: a haploid stage, called the gametophyte, and a diploid stage, called the sporophyte. The sporophyte is short-lived and remains dependent on its parent gametophyte. Vascular plants first appeared during the Silurian period, and by the Devonian had diversified and spread into many different land environments. They have a number of adaptations that allowed them to overcome the limitations of the bryophytes. These include a cuticle resistant to desiccation, and vascular tissues which transport water throughout the organism. In most the sporophyte acts as a separate individual, while the gametophyte remains small. Devonians (Pteridophyta) more closely allied to seed plants than they are to clubmosses (Lycopodiophyta)]] The first primitive seed plants, Pteridosperms (seed ferns) and Cordaites, both groups now extinct, appeared in the late Devonian and diversified through the Carboniferous, with further evolution through the Permian and Triassic periods. In these the gametophyte stage is completely reduced, and the sporophyte begins life inside an enclosure called a seed, which develops while on the parent plant, and with fertilisation by means of pollen grains. Whereas other vascular plants, such as ferns, reproduce by means of spores and so need moisture to develop, some seed plants can survive and reproduce in extremely arid conditions. Early seed plants are referred to as gymnosperms (naked seeds), as the seed embryo is not enclosed in a protective structure at pollination, with the pollen landing directly on the embryo. Four surviving groups remain widespread now, particularly the conifers, which are dominant trees in several biomes. The angiosperms, comprising the flowering plants, were the last major group of plants to appear, emerging from within the gymnosperms during the Jurassic and diversifying rapidly during the Cretaceous. These differ in that the seed embryo is enclosed, so the pollen has to grow a tube to penetrate the protective seed coat; they are the predominant group of flora in most biomes today.

Algae and Fungi

The algae comprise several different groups of organisms that produce energy through photosynthesis. However, they are not classified within the kingdom plantae but in the kingdom protista instead. The most conspicuous are the seaweeds, multicellular algae that often closely resemble terrestrial plants, but as stated above are not plants, found among the green, red, and brown algae. These and other algal groups also include various single-celled creatures and forms that are simple collections of cells, without differentiated tissues. Many can move about, and some have even lost their ability to photosynthesize; when first discovered, these were considered as both plants and animals. Now they are considered neither, but protists. The embryophytes developed from green algae; the two are collectively referred to as the green plants or Viridiplantae. The kingdom Plantae is now usually taken to mean this monophyletic group, as shown above. With a few exceptions among the green algae, all such forms have cell walls containing cellulose and chloroplasts containing chlorophylls a and b, and store food in the form of starch. They undergo closed mitosis without centrioles, and typically have mitochondria with flat cristae. The chloroplasts of green plants are surrounded by two membranes, suggesting they originated directly from endosymbiotic cyanobacteria. The same is true of the red algae, and the two groups are generally believed to have a common origin. In contrast, most other algae have chloroplasts with three or four membranes. They are not in general close relatives of the green plants, acquiring chloroplasts separately from ingested or symbiotic green and red algae. Unlike embryophytes and algae, fungi are not photosynthetic, but are saprophytes: they obtain their food by breaking down and absorbing surrounding materials. Most fungi are formed by microscopic tubes called hyphae, which may or may not be divided into cells but contain eukaryotic nuclei. Fruiting bodies, of which mushrooms are the most familiar, are actually only the reproductive structures of fungi. They are not related to any of the photosynthetic groups, but are close relatives of animals. Therefore, fungus has a kingdom of its own.

Importance

The photosynthesis and carbon fixation conducted by land plants and algae are the ultimate source of energy and organic material in nearly all habitats. These processes also radically changed the composition of the Earth's atmosphere, which as a result contains a large proportion of oxygen. Animals and most other organisms are aerobic, relying on oxygen; those that do not are confined to relatively few, anaerobic environments. Much of human nutrition depends on cereals. Other plants that are eaten include fruits, vegetables, herbs, and spices. Some vascular plants, referred to as trees and shrubs, produce woody stems and are an important source of building material. A number of plants are used decoratively, including a variety of flowers.

Growth

It is a common misconception that most of the solid material in a plant is taken from the soil, when in fact almost all of it is actually taken from the air. Through a process known as photosynthesis, plants use the energy in sunlight to convert carbon dioxide from the air into simple sugars. These sugars are then used as building blocks and form the main structural component of the plant. Plants rely on soil primarily for water (in quantitative terms), but also obtain nitrogen, phosphorus and other crucial nutrients. phosphorus Simple plants like algae may have short life spans as individuals, but their populations are commonly seasonal. Other plants may be organized according to their seasonal growth pattern:
- Annual: live and reproduce within one growing season.
- Biennial: live for two growing seasons; usually reproduce in second year.
- Perennial: live for many growing seasons; continue to reproduce once mature. Among the vascular plants, perennials include both evergreens that keep their leaves the entire year, and deciduous plants which lose their leaves for some part. In temperate and boreal climates, they generally lose their leaves during the winter; many tropical plants lose their leaves during the dry season. The growth rate of plants is extremely variable. Some mosses grow less than 0.001 mm/h, while most trees grow 0.025-0.250 mm/h. Some climbing species, such as kudzu, which do not need to produce thick supportive tissue, may grow up to 12.5 mm/h.

Fossils

Plant fossils include roots, wood, leaves, seeds, fruit, pollen, spores, phytoliths, and amber (the fossilized resin produced by some plants). Fossil land plants are recorded in terrestrial, lacustrine, fluvial and nearshore marine sediments. Pollen, spores and algae (dinoflagellates and acritarchs) are used for dating sedimentary rock sequences. The remains of fossil plants are not as common as fossil animals, although plant fossils are locally abundant in many regions worldwide. Early fossils of these ancient plants show the individual cells within the plant tissue. The Devonian period also saw the evolution of what many believe to be the first modern tree, Archaeopteris. This fern-like tree combined a woody trunk with the fronds of a fern, but produced no seeds. Archaeopteris The Coal Measures are a major source of Palaeozoic plant fossils, with many groups of plants in existence at this time. The spoil heaps of coal mines are the best places to collect; coal itself is the remains of fossilised plants, though structural detail of the plant fossils is rarely visible in coal. In the Fossil Forest at Victoria Park in Glasgow, Scotland, the stumps of Lepidodendron trees are found in their original growth positions. The fossilized remains of conifer and angiosperm roots, stems and branches may be locally abundant in lake and inshore sedimentary rocks from the Mesozoic and Caenozoic eras. Sequoia and its allies, magnolia, oak, and palms are often found. Petrified wood is common in some parts of the world, and is most frequently found in arid or desert areas were it is more readily exposed by erosion. Petrified wood is often heavily silicified (the organic material replaced by silicon dioxide), and the impregnated tissue is often preserved in fine detail. Such specimens may be cut and polished using lapidary equipment. Fossil forests of petrified wood have been found in all continents. Fossils of seed ferns such as Glossopteris are widely distributed throughout several continents of the southern hemisphere, a fact that gave support to Alfred Wegener's early ideas regarding Continental drift theory.

Distribution

References and further reading

- Kenrick, Paul & Crane, Peter R. (1997). The Origin and Early Diversification of Land Plants: A Cladistic Study. Washington, D. C.: Smithsonian Institution Press. ISBN 1-56098-730-8.
- Raven, Peter H., Evert, Ray F., & Eichhorn, Susan E. (2005). Biology of Plants (7th ed.). New York: W. H. Freeman and Company. ISBN 0-7167-1007-2.
- Taylor, Thomas N. & Taylor, Edith L. (1993). The Biology and Evolution of Fossil Plants. Englewood Cliffs, NJ: Prentice Hall. ISBN 0-13-651589-4.

External links

- [http://tolweb.org/tree?group=Green_plants&contgroup=Eukaryotes Tree of Life]
- Chaw, S.-M. et al. [http://mbe.library.arizona.edu/data/1997/1401/7chaw.pdf Molecular Phylogeny of Extant Gymnosperms and Seed Plant Evolution: Analysis of Nuclear 18s rRNA Sequences (pdf file)] Molec. Biol. Evol. 14 (1): 56-68. 1997.
- [http://florabase.calm.wa.gov.au/phylogeny/cronq88.html Interactive Cronquist classification]

Botanical and vegetation databases

- [http://www.efloras.org/index.aspx e-Floras (Flora of China, Flora of North America and others)]
- [http://plants.usda.gov/ United States of America]
- [http://rbg-web2.rbge.org.uk/FE/fe.html Flora Europaea]
- [http://www.anbg.gov.au/cpbr/databases/ Australia]
- [http://davesgarden.com/pdb/ 'Dave's Garden' horticultural plant database]
- [http://www.chilebosque.cl Chilean plants at Chilebosque] Category:Plants Category:Plant_taxonomy zh-min-nan:Si̍t-bu̍t ko:식물 ms:Tumbuhan ja:植物 simple:Plant th:พืช

Flowering plant

Magnoliopsida - Dicots
Liliopsida - Monocots
The flowering plants (also called angiosperms) are a major group of land plants. They comprise one of the two groups in the seed plants: the flowering plants cover their seeds by including them in a true fruit. They bear the reproductive organs in a structure called a flower; the ovule is enclosed within a carpel, which will lead to a fruit. In the other major group of seed plants, called gymnosperms, the ovule is not enclosed at pollination and the seeds are not in a true fruit, although occasionally fleshy structures may cover the seed (e.g. Taxus).

History

The botanical term "Angiosperm" (Greek: αγγειον, receptacle, and σπερμα, seed) was coined in the form Angiospermae by Paul Hermann in 1690, as the name of that one of his primary divisions of the plant kingdom, which included flowering plants possessing seeds enclosed in capsules, in contradistinction to his Gymnospermae, or flowering plants with achenial or schizo-carpic fruits—the whole fruit or each of its pieces being here regarded as a seed and naked. The term and its antonym were maintained by Carolus Linnaeus with the same sense, but with restricted application, in the names of the orders of his class Didynamia. Its use with any approach to its modern scope only became possible after Robert Brown had established in 1827 the existence of truly naked ovules in the Cycadeae and Coniferae, entitling them to be correctly called Gymnosperms. From that time onwards, so long as these Gymnosperms were, as was usual, reckoned as dicotyledonous flowering plants, the term Angiosperm was used antithetically by botanical writers, but with varying limitation, as a group-name for other dicotyledonous plants. The advent in 1851 of Hofmeister's brilliant discovery of the changes proceeding in the embryo-sac of flowering plants, and his determination of the correct relationships of these with the Cryptogamia, fixed the position of Gymnosperms as a class distinct from Dicotyledons, and the term Angiosperm then gradually came to be accepted as the suitable designation for the whole of the flowering plants other than Gymnosperms, and as including therefore the classes of Dicotyledons and Monocotyledons. This is the sense in which the term is nowadays received and in which it is used here.

Origins

The trend of the evolution of the plant kingdom has been in the direction of the establishment of a vegetation of fixed habit and adapted to the vicissitudes of a life on land, and the Angiosperms are the highest expression of this evolution and constitute the dominant vegetation of the earth's surface at the present epoch. There is no land-area from the poles to the equator, where plant-life is possible, upon which Angiosperms are not found. They also occur abundantly in the shallows of rivers and fresh-water lakes, and in less number in salt lakes and in the sea; such aquatic Angiosperms are not, however, primitive forms, but are derived from immediate land-ancestors. Associated with this diversity of habitat is great variety in general form and manner of growth. The familiar duckweed which covers the surface of a pond consists of a tiny green "thalloid" shoot, one, that is, which shows no distinction of parts—stem and leaf, and a simple root growing vertically downwards into the water. The great forest-tree has a shoot, which in the course perhaps of hundreds of years, has developed a wide-spreading system of trunk and branches, bearing on the ultimate twigs or branchlets innumerable leaves, while beneath the soil a widely-branching root-system covers an area of corresponding extent. Between these two extremes is every conceivable gradation, embracing aquatic and terrestrial herbs, creeping, erect or climbing in habit, shrubs and trees, and representing a much greater variety than is to be found in the other subdivision of seed-plants, the Gymnosperms. The first evidence of angiosperms appears in the fossil record approximately 140 million years ago, during the Jurassic period (203-135 million years ago). Based on current evidence, it seems that the ancestors of the angiosperms and the Gnetophytes diverged from one another during the late Triassic (220-202 million years ago). Fossil plants with some identifiable angiosperm characteristics appear in the Jurassic and early Cretaceous (135-65 million years ago), but in relatively few and primitive forms. The great angiosperm radiation, when a great diversity of angiosperms appear in the fossil record, occurred in the mid-Cretaceous (approximately 100 million years ago). By the late Cretaceous, angiosperms appear to have become the predominant group of land plants, and many fossil plants recognizable as belonging to modern families (including beech, oak, maple, and magnolia) appeared.

Classification

The flowering plants are usually treated as a division. As this is a group above the rank of family there is a free choice of name: Art 16 of the ICBN allows either a descriptive name or a name based on a generic name. The favorite name in the latter category is Magnoliophyta (at the rank of division, based on the Magnolia. The most popular descriptive name is Angiospermae (Angiosperms), with Anthophyta ("flowering plants") a second choice. The internal classification of this group has undergone considerable revision as ideas about their relationships change. The Cronquist system, proposed by Arthur Cronquist in 1981, is still widely used but is no longer believed to reflect phylogeny. A general consensus about how the flowering plants should be arranged has only recently begun to emerge, through the work of the Angiosperm Phylogeny Group, who published an influential reclassification of the angiosperms in 1998. An update incorporating more recent research was published as APG (2003) and is available at the Wikipedia Tree of Life/Update of the Angiosperm Phylogeny Group. Traditionally, the flowering plants are divided into two groups, which in the Cronquist system are called Magnoliopsida (at the rank of class, based on Magnolia) and Liliopsida (at the rank of class, based on Lilium). Much more popular are their descriptive names (as allowed by Art 16 of the ICBN): Dicotyledones (some prefer Dicotyledoneae) and Monocotyledones (some prefer Monocotyledoneae), which have been in use for very long. In English a member of either group may be called a "dicotyledon" (plural "dicotyledons") and "monocotyledon" (plural "monocotyledons"), or more popularly "dicot" (plural "dicots") and "monocot" (plural "monocots"). These names derive from the fact that the dicots often (but not always) have two cotyledons (embryonic leaves) within each seed, while the monocots typically will have one only. From a diagnostic point of view the number of cotyledons is neither a particularly handy nor reliable character. Recent studies show that the monocots are a "good" group (a holophyletic or monophyletic group), while the dicots are not (a paraphyletic group). However, within the dicots a "good" group exists, which includes most of the dicots. This new group is semi-informally called the "eudicots" or "tricolpates". The name "tricolpates" derives from the type of pollen found throughout this group. The name eudicots is formed by preceding "dicot" by the prefix "eu-" (greek 'eu'= "true"), as the eudicots share the characters traditionally attributed to the dicots, such a four- or five-merous flowers. The uninitiate may be tempted to jump to the conclusion that "eudicot" is short for "eudicotyledon" but it is not: the name is eudicot. A formal name that is sometimes used for this group is Rosopsida (at the rank of class, based on Rosa). Separating this group of eudicots from the rest of the (former) dicots leaves a remainder, which sometimes are called informally "palaeodicots" (the prefix "palaeo-" means old, and derives from the classic greek). As this remainder group is not a "good" group this is a term of convenience only.

Families of flowering plants

The most diverse families of flowering plants, in order of number of species, are: palaeodicot flower]] # Asteraceae or Compositae (Daisy family): 26,000 species # Orchidaceae (Orchid family): 20,000 (possibly 30,000) # Fabaceae or Leguminosae (Pea family): 17,000 # Poaceae or Gramineae (Grass family): 9,000 # Rubiaceae (Madder family): 7,000 # Euphorbiaceae (Spurge family): 5,000 # Malvaceae (Mallow family): 4,300 # Cyperaceae (Sedge family): 4,000 In the list above (showing only the 8 largest families), the Orchidaceae, Poaceae, and Cyperaceae are monocot families; the others are dicot families. The total number of families in the flowering plants is over 460.

Internal structure

In internal structure the variety of tissue-formation far exceeds that found in Gymnosperms. The vascular bundles of the stem belong to the collateral type, that is to say, the elements of the wood or xylem and the bast or phloem stand side by side on the same radius. In the larger of the two great groups into which the Angiosperms are divided, the Dicotyledons, the bundles in the very young stem are arranged in an open ring, separating a central pith from an outer cortex. In each bundle, separating the xylem and phloem, is a layer of meristem or active formative tissue, known as cambium; by the formation of a layer of cambium between the bundles (interfascicular cambium) a complete ring is formed, and a regular periodical increase in thickness results from it by the development of xylem on the inside and phloem on the outside. The soft phloem soon becomes crushed, but the hard wood persists, and forms the great bulk of the stem and branches of the woody perennial. Owing to differences in the character of the elements produced at the beginning and end of the season, the wood is marked out in transverse section into concentric rings, one for each season of growth—the so-called annual rings. In the smaller group, the Monocotyledons, the bundles are more numerous in the young stem and scattered through the ground tissue. Moreover they contain no cambium and the stem once formed increases in diameter only in exceptional cases.

Vegetative organs

As in Gymnosperms, branching is monopodial; dichotomy or the forking of the growing point into two equivalent branches which replace the main stem, is absent both in the case of the stem and the root. The leaves show a remarkable variety in form, but are generally small in comparison with the size of the plant; exceptions occur in some Monocotyledons, e.g. in the Aroid family, where in some genera the plant produces one huge, much-branched leaf each season. In rare cases the main axis is unbranched and ends in a flower, as, for instance, in the tulip, where scale-leaves, forming the underground bulb, green foliage-leaves and coloured floral leaves are borne on one and the same axis. Generally, flowers are formed only on shoots of a higher order, often only on the ultimate branches of a much branched system. A potential branch or bud, either foliage or flower, is formed in the axil of each leaf; sometimes more than one bud arises, as for instance in the walnut, where two or three stand in vertical series above each leaf. Many of the buds remain dormant, or are called to development under exceptional circumstances, such as the destruction of existing branches. For instance, the clipping of a hedge or the lopping of a tree will cause to develop numerous buds which may have been dormant for years. Leaf-buds occasionally arise from the roots, when they are called adventitious; this occurs in many fruit trees, poplars, elms and others. For instance, the young shoots seen springing from the ground around an elm are not seedlings but root-shoots. Frequently, as in many Dicotyledons, the primary root, the original root of the seedling, persists throughout the life of the plant, forming, as often in biennials, a thickened tap-root, as in carrot, or in perennials, a much-branched root system. In many Dicotyledons and most Monocotyledons, the primary root soon perishes, and its place is taken by adventitious roots developed from the stem.

The flower, fruit, and seed

- See main article: Flower The characteristic feature of angiosperms is the flower, which shows remarkable variation in form and elaboration, and provides the most trustworthy external characteristics for establishing relationships among angiosperm species. The function of the flower is that of ensuring fertilization of the ovule and development of fruit containing seeds. The floral apparatus may arise terminally on a shoot or from the axil of a leaf. Occasionally, as in violet, a flower arises singly in the axil of an ordinary foliage-leaf. However, more typically, the flower-bearing portion of the plant is sharply distinguished from the foliage-bearing or vegetative portion, and forms a more or less elaborate branch-system called an inflorescence. As in gymnosperms, spores produced by flowers are of two kinds: microspores or pollen-grains, borne in the stamens (or microsporophylls) and megaspores, in which the egg-cell is developed, contained in the ovule and enclosed in the carpel (or megasporophyll). The flower may consist only of these spore-bearing parts, as in willow, where each flower comprises only a few stamens or two carpels. Usually, however, other structures are present and serve both to protect the sporophylls and to form an attractive envelope. The individual members of these surrounding structures are called sepals and petals (or tepals in a flower such as Michelia). The outer series (calyx of sepals) is usually green and leaf-like, and functions to protect the rest of the flower, especially in the bud. The inner series (corolla of petals) is generally white or brightly coloured, and more delicate in structure, and functions in attracting a particular insect or bird by agency of which pollination is effected. This attraction involves colour and scent, and frequently also nectar which is secreted in some part of the flower. These characteristics that attract pollinators account for the popularity of flowers and flowering plants among humans.

Flowering plant sexuality

- See main article: Plant sexuality Flowers are the reproductive structures of flowering plants. The "male" organ is the stamen or androecium, which produces pollen (male spores) in anthers. The "female" organ is the carpel or gynoecium, which contains the egg (female gamete) and is the site of fertilization. While the majority of flowers are perfect or hermaphrodite (having both male and female parts in the same flower structure), flowering plants have developed numerous morphological and physiological mechanisms to reduce or prevent self-fertilization. Heteromorphic flowers have short carpels and long stamens, or vice versa, so animal pollinators cannot easily transfer pollen to the pistil (receptive part of the carpel). Homomorphic flowers may employ a biochemical (physiological) mechanism called self-incompatibility to discriminate between self- and non-self pollen grains. In other species, the male and female parts are morphologically separated, developing on different flowers.

Fertilization

At the period of fertilization the embryo-sac lies in close proximity to the opening of the micropyle, into which the pollen-tube has penetrated, the separating cell-wall becomes absorbed, and the male or sperm-cells are ejected into the embryo-sac. Guided by the synergidae one male-cell passes into the oosphere with which it fuses, the two nuclei uniting, while the other fuses with the definitive nucleus, or, as it is also called, the endosperm nucleus. This remarkable double fertilization as it has been called, although only recently discovered, has been proved to take place in widely-separated families, and both in Monocotyledons and of a prothallium after a pause following the reinvigorating union of the polar nuclei. This view is still maintained by those who differentiate two acts of fertilization within the embryo-sac, and regard that of the egg by the first male-cell, as the true or generative fertilization, and that of the polar nuclei by the second male gamete as a vegetative fertilization which gives a stimulus to development in correlation with the other. If, on the other hand, the endosperm is the product of an act of fertilization as definite as that giving rise to the embryo itself, we have to recognize that twin-plants are produced within the embryo-sac—one, the embryo, which becomes the angiospermous plant, the other, the endosperm, a short-lived, undifferentiated nurse to assist in the nutrition of the former, even as the subsidiary embryos in a pluri-embryonic Gymnosperm may facilitate the nutrition of the dominant one. If this is so, and the endosperm like the embryo is normally the product of a sexual act, hybridization will give a hybrid endosperm as it does a hybrid embryo, and herein (it is suggested) we may have the explanation of the phenomenon of xenia observed in the mixed endosperms of hybrid races of maize and other plants, regarding which it has only been possible hitherto to assert that they were indications of the extension of the influence of the pollen beyond the egg and its product. This would not, however, explain the formation of fruits intermediate in size and colour between those of crossed parents. The signification of the coalescence of the polar nuclei is not explained by these new facts, but it is noteworthy that the second male-cell is said to unite sometimes with the apical polar nucleus, the sister of the egg, before the union of this with the basal polar one. The idea of the endosperm as a second subsidiary plant is no new one; it was suggested long ago in explanation of the coalescence of the polar nuclei, but it was then based on the assumption that these represented male and female cells, an assumption for which there was no evidence and which was inherently improbable. The proof of a coalescence of the second male nucleus with the definitive nucleus gives the conception a more stable basis. The antipodal cells aid more or less in the process of nutrition of the developing embryo, and may undergo multiplication, though they ultimately disintegrate, as do also the synergidae. As in Gymnosperms and other groups an interesting qualitative change is associated with the process of fertilization. The number of chromosomes (see Plant cytology) in the nucleus of the two spores, pollen-grain and embryo-sac, is only half the number found in an ordinary vegetative nucleus; and this reduced number persists in the cells derived from them. The full number is restored in the fusion of the male and female nuclei in the process of fertilization, and remains until the formation of the cells from which the spores are derived in the new generation. In several natural orders and genera departures from the course of development just described have been noted. In the natural Order Rosaceae, the Series Querciflorae, and the very anomalous Genus Casuarina and others, instead of a single macrospore a more or less extensive sporogenous tissue is formed, but only one cell proceeds to the formation of a functional female cell. In Casuarina, Juglans and the Order Corylaceae, the pollen-tube does not enter by means of the micropyle, but passing down the ovary wall and through the placenta, enters at the chalazal end of the ovule. Such a method of entrance is styled chalazogamic, in contrast to the porogamic or ordinary method of approach by means of the micropyle.

Embryology

The result of fertilization is the development of the ovule into the seed. By the segmentation of the fertilized egg, now invested by cell-membrane, the embryo-plant arises. A varying number of transverse segment-walls transform it into a pro-embryo—a cellular row of which the cell nearest the micropyle becomes attached to the apex of the embryo-sac, and thus fixes the position of the developing embryo, while the terminal cell is projected into its cavity. In Dicotyledons the shoot of the embryo is wholly derived from the terminal cell of the pro-embryo, from the next cell the root arises, and the remaining ones form the suspensor. In many Monocotyledons the terminal cell forms the cotyledonary portion alone of the shoot of the embryo, its axial part and the root being derived from the adjacent cell; the cotyledon is thus a terminal structure and the apex of the primary stem a lateral one—a condition in marked contrast with that of the Dicotyledons. In some Monocotyledons, however, the cotyledon is not really terminal. The primary root of the embryo in all Angiosperms points towards the micropyle. The developing embryo at the end of the suspensor grows out to a varying extent into the forming endosperm, from which by surface absorption it derives good material for growth; at the same time the suspensor plays a direct part as a carrier of nutrition, and may even develop, where perhaps no endosperm is formed, special absorptive "suspensor roots" which invest the developing embryo, or pass out into the body and coats of the ovule, or even into the placenta. In some cases the embryo or the embryo-sac sends out suckers into the nucellus and ovular integument. As the embryo develops it may absorb all the food material available, and store, either in its cotyledons or in its hypocotyl, what is not immediately required for growth, as reserve-food for use in germination, and by so doing it increases in size until it may fill entirely the embryo-sac; or its absorptive power at this stage may be limited to what is necessary for growth and it remains of relatively small size, occupying but a small area of the embryo-sac, which is otherwise filled with endosperm in which the reserve-food is stored. There are also intermediate states. The position of the embryo in relation to the endosperm varies, sometimes it is internal, sometimes external, but the significance of this has not yet been established. The formation of endosperm starts, as has been stated, from the endosperm nucleus. Its segmentation always begins before that of the egg, and thus there is timely preparation for the nursing of the young embryo. If in its extension to contain the new formations within it the embryo-sac remains narrow, endosperm formation proceeds upon the lines of a cell-division, but in wide embryo-sacs the endosperm is first of all formed as a layer of naked cells around the wall of the sac, and only gradually acquires a pluricellular character, forming a tissue filling the sac. The function of the endosperm is primarily that of nourishing the embryo, and its basal position in the embryo-sac places it favourably for the absorption of food material entering the ovule. Its duration varies with the precocity of the embryo. It may be wholly absorbed by the progressive growth of the embryo within the embryo-sac, or it may persist as a definite and more or less conspicuous constituent of the seed. When it persists as a massive element of the seed its nutritive function is usually apparent, for there is accumulated within its cells reserve-food, and according to the dominant substance it is starchy, oily, or rich in cellulose, mucilage or proteid. In cases where the embryo has stored reserve food within itself and thus provided for self-nutrition, such endosperm as remains in the seed may take on other functions, for instance, that of water-absorption. Some deviations from the usual course of development may be noted. Parthenogenesis, or the development of an embryo from an egg-cell without the latter having been fertilized, has been described in species of Thalictrum, Antennaria and Alchemilla. Polyembryony is generally associated with the development of cells other than the egg-cell. Thus in Erythronium and Limnocharis the fertilized egg may form a mass of tissue on which several embryos are produced. Isolated cases show that any of the cells within the embryo-sac may exceptionally form an embryo, e.g. the synergidae in species of Mimosa, Iris and Allium, and in the last-mentioned the antipodal cells also. In Coelebogyne (Euphorbiaceae) and in Funkia (Liliaceae) polyembryony results from an adventitious production of embryos from the cells of the nucellus around the top of the embryo-sac. In a species of Allium, embryos have been found developing in the same individual from the egg-cell, synergids, antipodal cells and cells of the nucellus. In two Malayan species of Balanophora, the embryo is developed from a cell of the endosperm, which is formed from the upper polar nucleus only, the egg apparatus becoming disorganized. The last-mentioned case has been regarded as representing an apogamous development of the sporophyte from the gametophyte comparable to the cases of apogamy described in Ferns. But the great diversity of these abnormal cases as shown in the examples cited above suggests the use of great caution in formulating definite morphological theories upon them.

Fruit and seed

As the development of embryo and endosperm proceeds within the embryo-sac, its wall enlarges and commonly absorbs the substance of the nucellus (which is likewise enlarging) to near its outer limit, and combines with it and the integument to form the seed-coat; or the whole nucellus and even the integument may be absorbed. In some plants the nucellus is not thus absorbed, but itself becomes a seat of deposit of reserve-food constituting the perisperm which may coexist with endosperm, as in the water-lily order, or may alone form a food-reserve for the embryo, as in Canna. Endospermic food-reserve has evident advantages over perispermic, and the latter is comparatively rarely found and only in non-progressive series. Seeds in which endosperm or perisperm or both exist are commonly called albuminous or endospermic, those in which neither is found are termed exalbuminous or exendospermic. These terms, extensively used by systematists, only refer, however, to the grosser features of the seed, and indicate the more or less evident occurrence of a food-reserve; many so-called exalbuminous seeds show to microscopic examination a distinct endosperm which may have other than a nutritive function. The presence or absence of endosperm, its relative amount when present, and the position of the embryo within it, are valuable characters for the distinction of orders and groups of orders. Meanwhile the ovary wall has developed to form the fruit or pericarp, the structure of which is closely associated with the manner of distribution of the seed. Frequently the influence of fertilization is felt beyond the ovary, and other parts of the flower take part in the formation of the fruit, as the floral receptacle in the apple, strawberry and others. The character of the seed-coat bears a definite relation to that of the fruit. Their function is the twofold one of protecting the embryo and of aiding in dissemination; they may also directly promote germination. If the fruit is a dehiscent one and the seed is therefore soon exposed, the seed-coat has to provide for the protection of the embryo and may also have to secure dissemination. On the other hand, indehiscent fruits discharge these functions for the embryo, and the seed-coat is only slightly developed.

Economic importance

Flowering plants provide a very high percentage of the base food for human use, whether directly or through livestock feed. Of all the families of flowering plants, the Poaceae, or grass family, is by far the most important, providing the bulk of all feedstocks (rice, corn (maize), wheat, barley, rye, oats, millet, sugar cane, sorghum), with the Fabaceae, or legume family, in second place. Also of high importance are the Solanaceae, or nightshade family (potatoes, tomatoes, and peppers, among others), the Cucurbitaceae, or gourd family (also including pumpkins and melons), the Brassicaceae, or mustard family (including rapeseed and cabbage), and the Apiaceae, or parsley family. Many of our fruits come from the Rutaceae, or rue family, and the Rosaceae (rose family, including apples, pears, cherries, apricots, plums, etc). In some parts of the world, certain single species assume paramount importance because of their variety of uses. An example is the coconut (Cocos nucifera) on Pacific atolls. Another example is the olive (Olea europaea) in the Mediterranean. Flowering plants also provide economic resources in the form of wood, paper, fiber (cotton, flax, and hemp, among others), medicines (digitalis, camphor), decorative and landscaping plants, and many, many other uses.

References and external links

- Angiosperm Phylogeny Group (2003). An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG II. Botanical Journal of the Linnean Society 141: 399-436. [http://www.blackwell-synergy.com/links/doi/10.1046/j.1095-8339.2003.t01-1-00158.x/full/ Available online].
- [http://tolweb.org/tree?group=Angiosperms&contgroup=Spermatopsida Angiosperms] – Tree of Life Web Project
- Cronquist, Arthur. (1981) An Integrated System of Classification of Flowering Plants. Columbia Univ. Press, New York.
- [http://www.news.harvard.edu/gazette/1999/12.16/angiosperms.html Oldest Known Flowering Plants Identified By Genes], William J. Cromie, Harvard Gazette, December 16, 1999.
- Stevens, P.F. (2001 onwards). [http://www.mobot.org/MOBOT/Research/APweb/welcome.html Angiosperm Phylogeny Website] at Missouri Botanical Garden.
- [http://delta-intkey.com/angio/ L. Watson and M.J. Dallwitz (1992 onwards). The families of flowering plants: descriptions, illustrations, identification, information retrieval.] http://delta-intkey.com Category:Magnoliophyta sort31 Angiospermae sort31 Angiospermae Category:Sexuality Category:Pollination ko:속씨식물 ms:Angiosperm ja:被子植物門 th:ไม้ดอก

Seed

A seed is the ripened ovule of gymnosperm or angiosperm plants. The importance of the seed relative to more primitive forms of reproduction and dispersal is attested to by the success of these two groups of plants in dominating the landscape.

Seed structure

A fertilized seed contains the embryo from which a new plant will grow under proper conditions. It also contains a supply of stored food and is wrapped in the seed coat or testa. The stored food begins as a tissue called endosperm derived from the parent plant. Endosperm becomes rich in oil or starch, and protein. In some species, the embryo is imbedded in the endosperm, which the seedling will use upon germination. In others, the endosperm is absorbed by the embryo as the latter grows within the developing seed, and the cotyledons of the embryo become filled with this stored food. At maturity, seeds of these species have no endosperm. Some common plant seeds that lack an endosperm are bean, pea, oak, walnut, squash, sunflower, and radish. Plant seeds with an endosperm include all conifers and most monocotyledons (e.g. grasses and palms), and also e.g. brazil nut, castor bean. castor bean See also: Hypocotyl The seed coat develops from tissues (called integument) originally surrounding the ovule. The seed coat in the mature seed can be a paper thin layer (as for example, in the peanut) or something more substantial (as for example, thick and hard in honey locust and coconut). The seed coat helps protect the embryo from mechanical injury and from drying out. In order for the seed coat to split, the embryo must imbibe (soak up water) which causes it to swell, splitting the seed coat. However, the nature of the seed coat determines how rapidly water can penetrate and subsequently initiate germination. For seeds with a very thick coat, scarification of the seed coat may be necessary before water can reach the embryo. Examples of scarification include: gnawing by animals, freezing and thawing, battering on rocks in a stream bed, or passing through an animal's digestive tract. In the latter case, the seed coat protects the seed from digestion, while perhaps weakening the seed coat such that the embryo is ready to sprout when it gets deposited (along with a bit of fertilizer) far from the parent plant. In species with thin seed coats, light may be able to penetrate into the dormant embryo. The presence of light or the absence of light may trigger the germination process, inhibiting germination in some seeds buried too deeply or in others not buried in the soil. Abscisic acid is usually the growth inhibitor in seeds. The seeds of angiosperms are contained in a hard or fleshy (or with layers of both) structure called a fruit. Gymnosperm seeds begin their development "naked" on the bracts of cones, although the seeds do become covered by the cone scales as they develop. An example of a hard fruit layer surrounding the actual seed is that of the so-called stone fruits (such as the peach).

Seed functions

Unlike animals, plants are limited in their ability to seek out favorable conditions for life and growth. Consequently, plants have evolved many ways to disperse and spread the population through their seeds (see also vegetative reproduction). A seed must somehow "arrive" at a location and be there at a time favorable for germination and growth. Those properties or attributes that promote the movement of the next generation away from the parent plant may involve the fruit more so than the seeds themselves. The function of a seed typically is one of serving as a delaying mechanism: a way for the new generation to suspend its growth and allow time for dispersal to occur or to survive harsh, unfavorable conditions of cold or dryness or both. In many if not most cases each plant species achieves success in finding ideal locations for placement of its seeds through the basic approach of producing numerous seeds. This is certainly the approach used by plants, such as ferns, that disperse by spores. However, seeds involve a considerably greater investment in energy and resources than do spores, and the payoff must come in achieving similar or greater success with fewer dispersal units.

External links

- [http://www.seedlab.co.nz/NAMESEED.HTM List of Common Botanical Seed Names]
- [http://theseedsite.co.uk/ The Seed Site]: collecting, storing, sowing, germinating, and exchanging seeds, with pictures of seeds, seedpods and seedlings. Category:Plants Category: plant morphology Category:Vegetables Category:Flowers ko:씨 ja:種子 simple:Seed

Fruit

In botany, a fruit is the ripened ovary—together with seeds—of a flowering plant. In many species, the fruit incorporates the ripened ovary and surrounding tissues. Fruits are the means by which flowering plants disseminate seeds. Evolution has led plants to adopt certain basic mechanisms, seemingly without close regard to the tissues involved. No one terminology really fits the enormous variety that is found among plant fruits. Botanical terminology for fruits is inexact and will remain so. In cuisine, when discussing fruit as food, the term usually refers to just those plant fruits that are sweet and fleshy, examples of which include plum, apple and orange. However, a great many common vegetables, as well as nuts and grains, are the fruit of the plant species they come from. The term false fruit (pseudocarp, accessory fruit) is sometimes applied to a fruit like the fig (a multiple-accessory fruit; see below) or to a plant structure that resembles a fruit but is not derived from a flower or flowers. Some gymnosperms, such as yew, have fleshy arils that resemble fruits and some junipers have berry-like, fleshy cones. With most fruits pollination is a vital part of fruit culture, and the lack of knowledge of pollinators and pollenizers can contribute to poor crops or poor quality crops. In a few species, the fruit may develop in the absence of pollination/fertilization, a process known as parthenocarpy. Such fruits are seedless. A plant that does not produce fruit is known as acarpous, meaning essentially "without fruit".

Botanic fruits and culinary fruits

Many foods are botanically a fruit, but are treated as vegetables in cooking. These include cucurbits (e.g. squash and pumpkin), maize, tomatoes, cucumber, aubergines (eggplants) and green peppers, along with nuts, and some spices, such as allspice, nutmeg and chiles. Rarely, culinary "fruits" are not fruits in the botanical sense. For example, rhubarb may be considered a fruit, though only the astringent stalk, or petiole, is edible. In the commercial world, European Union rules define carrot as a fruit for the purposes of measuring the proportion of "fruit" contained in carrot jam.

Fruit development

After an ovule is fertilized in a process known as pollination, the ovary begins to expand. The petals of the flower fall off and the ovule develops into a seed. The ovary eventually comes to form, along with other parts of the flower in many cases, a structure surrounding the seed or seeds that is the fruit. Fruit development continues until the seeds have matured. With some multiseeded fruits the extent of development of the flesh of the fruit is proportional to the number of fertilized ovules. The wall of the fruit, developed from the ovary wall of the flower, is called the pericarp. The pericarp is often differentiated into two or three distinct layers called the exocarp (outer layer - also called epicarp), mesocarp (middle layer), and endocarp (inner layer). In some fruits, especially simple fruits derived from an inferior ovary, other parts of the flower (such as the floral tube, including the petals, sepals, and stamens), fuse with the ovary and ripen with it. When such other floral parts are a significant part of the fruit, it is called an accessory fruit. Since other parts of the flower may contribute to the structure of the fruit, it is important to study flower structure to understand how a particular fruit forms. Fruits are so varied in form and development, that it is difficult to devise a classification scheme that includes all known fruits. It will also be seen that many common terms for seeds and fruit are incorrectly applied, a fact that complicates understanding of the terminology. Seeds are ripened ovules; fruits are the ripened ovularies or carpels that contain the seeds. To these two basic definitions can be added the clarification that in botanical terminology, a nut is a type of fruit and not another term for seed. There are three basic types of fruits: # Simple fruit # Aggregate fruit # Multiple fruit

Simple fruit

Simple fruits can be either dry or fleshy and result from the ripening of a simple or compound ovary with only one pistil. Dry fruits may be either dehiscent (opening to discharge seeds), or indehiscent (not opening to discharge seeds). Types of dry, simple fruits (with examples) are:
- achene - (buttercup)
- capsule - (Brazil nut)
- caryopsis - (wheat)
- fibrous drupe - (coconut, walnut)
- follicle - (milkweed)
- legume - (pea, bean, peanut)
- loment
- nut - (hazelnut, beech, oak acorn)
- samara - (elm, ash, maple key)
- schizocarp - (carrot)
- silique - (radish)
- utricle Fruits in which part or all of the pericarp (fruit wall) is fleshy at maturity are simple fleshy fruits. Types of fleshy, simple fruits (with examples) are:
- berry - (tomato, avocado)
- drupe - (plum, cherry, peach, olive)
- false berry - accessory fruits (banana, cranberry)
- pome - accessory fruits (apple, pear, rosehip)

Aggregate fruit

rosehip An aggregate fruit, or etaerio, develops from a flower with numerous simple pistils. An example is the raspberry, whose simple fruits are termed drupelets because each is like a small drupe attached to the receptacle. In some bramble fruits (such as blackberry) the receptacle is elongate and part of the ripe fruit, making the blackberry an aggregate-accessory fruit. The strawberry is also an aggregate-accessory fruit, only one in which the seeds are contained in achenes. In all these examples, the fruit develops from a single flower with numerous pistils.

Multiple fruit

A multiple fruit is one formed from a cluster of flowers (called an inflorescence). Each flower produces a fruit, but these mature into a single mass. Examples are the pineapple, edible fig, mulberry, osage-orange, and breadfruit. breadfruit In the photograph on the right, stages of flowering and fruit development in the noni or Indian mulberry (Morinda citrifolia) can be observed on a single branch. First an inflorescence of white flowers called a head is produced. After fertilization, each flower develops into a drupe, and as the drupes expand, they connate (merge) into a multiple fleshy fruit called a syncarp.

Seedless Fruits

Seedlessness is an important feature of some fruits of commerce. Commercial cultivars of bananas and pineapples are seedless. Some cultivars of citrus fruits (especially navel oranges and mandarin oranges), table grapes, grapefruit, and watermelons are valued for their seedlessness. In some species, seedlessness is the result of parthenocarpy, where fruits set without fertilization. Parthenocarpic fruit set may or may not require pollination. Most seedless citrus fruits require a pollination stimulus; bananas and pineapples do not. Seedlessness in table grapes results from the abortion of the embryonic plant that is produced by fertilization, a phenomenon known as stenospermocarpy which requires normal pollination and fertilization.

Seed dissemination

Variations in fruit structures largely relate to dissemination (called dispersal) of the seeds they contain. Some fruits have coats covered with spikes or hooked burrs, either to prevent themselves from being eaten by animals or to stick to the hairs of animals, using them as dispersal agents. Other fruits are elongated and flattened out naturally and so become thin, like wings or helicopter blades. This is an evolutionary mechanism to increase dispersal distance away from the parent.

Uses

Many fruits, including fleshy fruits like apple and mango, and nuts like walnut, are commercially valuable as human food, eaten both fresh and made into jams, marmalade and other preserves for future consumption. Fruits are also found commonly in such manufactured foods as cookies, muffins, yoghurt, ice cream, cakes, and many more.

Pollen

), morning glory (Ipomea purpurea), hollyhock (Sildalcea malviflora), lily (Lilium auratum), primrose (Oenothera fruticosa), and castor bean (Ricinus communis).]] Pollen is a fine to coarse powder consisting of microgametophytes (pollen grains), which carry the male gametes of seed plants. Each pollen grain contains one or two generative cells (the male gametes) and a vegetative cell. The group of three cells is surrounded by a cellulose cell wall and a thick, tough outer wall made of sporopollenin. Pollen is produced in the microsporangium (anther of an angiosperm flower or male cone of a coniferous plant). Pollen grains come in a wide variety of shapes, sizes, and surface markings characteristic of the species (see photomicrograph at right). Most, but certainly not all, are spherical. Pollen grains of pines, firs, and spruces are winged. The smallest pollen grain, that of the Forget-me-not plant (Myosotis sp.), is around 6 µm (0.006 mm) in diameter. The study of pollen is called palynology and is highly useful in paleontology, archeology, and forensics. Except in the case of some submerged aquatic plants the mature pollen-grain has a double wall, a thin delicate wall of unaltered cellulose (the endospore or intine) and a tough outer cuticularized exospore or exine. The exine often bears spines or warts, or is variously sculptured, and the character of the markings is often of value for identifying genus, species, or even cultivar or individual. Germination of the microspore begins before it leaves the pollen-sac. In very few cases has anything representing prothallial development been observed; generally a small cell (the antheridial or generative cell) is cut off, leaving a larger tube-cell. The transfer of pollen grains to the female reproductive structure (pistil in angiosperms) is called pollination. This transfer can be mediated by the wind, in which case the plant is described as anemophilous (literally wind-loving). Anemophilous plants typically produce great quantities of very lightweight pollen grains, often with air-sacs, and generally have inconspicuous flowers. Entomophilous (literally insect-loving) plants produce pollen that is relatively heavy, sticky and protein-rich, for dispersal by insect pollinators attracted to their flowers. When placed on the stigma, under favorable circumstances, the pollen-grain puts forth a pollen-tube which grows down the tissue of the style to the ovary, and makes its way along the placenta, guided by projections or hairs, to the mouth of an ovule. The nucleus of the tube-cell has meanwhile passed into the tube, as does also the generative nucleus which divides to form two male- or sperm-cells. The male-cells are carried to their destination in the tip of the pollen-tube.

Hay fever

Main article: Hay fever Allergy to pollen is called hay fever. Generally pollens that cause allergies are those of anemophilous, because the lightweight pollen grains are produced in great quantities for wind dispersal. Breathing air containing these pollen grains brings them into contact with the nasal passages. In the US, people often falsely blame the conspicuous entomophilous goldenrod flower for allergies. Since this pollen does not become airborne, the only way to get goldenrod pollen on the nasal passages would be to stick the flower up one's nose. The late summer and fall pollen allergies are usually caused by ragweed, a widespread anemophilous plant. Arizona was once regarded as a haven for people with pollen allergies, since ragweed does not grow in the desert. However, as suburbs grew and people began establishing irrigated lawns and gardens, ragweed gained a foothold and Arizona lost its claim of freedom from hay fever. Anemophilous spring blooming plants such as oak, birch, hickory, pecan, and early summer grasses may also induce pollen allergies. Cultivated flowers are most often entomophilous and do not cause allergies.

Miscellaneous

The "tapping panel dryness disease" of the rubber plant is caused by a virus transmitted on pollen grains. virus Pollen is sold as a nutritional supplement, marketed as "bee pollen" (even though it is of course from flowers). There is doubt amongst conventional practitioners that taking pollen has any biological effect, although may possibly cause allergic reactions in sensitive people. Many trees and flowering plants are a good source of pollen for honeybees. Bees will collect pollen from some grasses and grains when they cannot find pollens with more nutritional value, however, anemophilous plants such as grasses generally have very low real value to bees. Some windblown pollen is likely to be inadvertently collected by bees, since they bear a static charge. Ragweed and pine pollen can settle on leaves and other flowers, to add to the total quantity of pollens that are found upon analysis of gathered pollen.

External links

static
- [http://www.geo.arizona.edu/palynology/polident.html Pollen and Spore Identification Literature]
- [http://www.flmnh.ufl.edu/natsci/paleobotany/paleobotany.htm Paleobotany and Palynology at the Florida Museum of Natural History]
- [http://www.geo.arizona.edu/palynology/ Palynology at the University of Arizona]
- [http://www.shef.ac.uk/uni/academic/N-Q/palysc/palyshef.html Palynology at the University of Sheffield]
- [http://www.bio.uu.nl/~palaeo/Engels/engels.html Palynology in Utrecht, the Netherlands]
- [http://www.quackwatch.org/01QuackeryRelatedTopics/DSH/bee.html Bee Pollen, Royal Jelly, and Propolis] - A sceptical view of the benefits of taking bee pollen.
- [http://www.watchtower.org/library/g/2003/7/22a/article_01.htm Pollen - Menace or Miracle?], discussion on its purpose in biology and as an allergen Category:Botany Category: plant anatomy Category: plant morphology Category:Pollination ja:花粉

Flower

Flower anatomy

Floral formula

Flower function

Flowers in gardening and horticulture

Main and related articles at: Gardening, Horticulture, List of flowers, and Flower album Flower album

Flowers in the arts

Flowers in everyday life

Flowers as symbols

References

- Eames, A. J. 1961. Morphology of the Angiosperms. McGraw-Hill Book Co., New York.

External links

Leaf

:This article is about the leaf, a plant organ. See Leaf (disambiguation) for other meanings. ---- In botany, a leaf is an above-ground plant organ specialized for photosynthesis. For this purpose, a leaf is typically flat (laminar) and thin, to expose the chloroplast containing cells (chlorenchyma tissue) to light over a broad area, and to allow light to penetrate fully into the tissues. Leaves are also the sites in most plants where respiration, transpiration, and guttation take place. Leaves can store food and water, and are modified in some plants for other purposes. The comparable structures of ferns are correctly referred to as fronds. frond frond frond

Leaf anatomy

A structurally complete leaf of an angiosperm consists of a petiole (leaf stem), a lamina (leaf blade), and stipules (small processes located to either side of the base of the petiole). The point at which the petiole attaches to the stem is called the leaf axil. Not every species produces leaves with all of these structural parts. In some species, paired stipules are not obvious or are absent altogether; a petiole may be absent; or the blade may not be laminar (flattened). The tremendous variety shown in leaf structure (anatomy) from species to species is presented in detail below under Leaf types, arrangements, and forms. A leaf is considered to be a plant organ, typically consisting of the following tissues: # An epidermis that covers the upper and lower surfaces # An interior chlorenchyma called the mesophyll # An arrangement of veins (the vascular tissue). stipule

Epidermis

The epidermis is the outer multi-layered group of cells covering the leaf. It forms the boundary between the plant and the external world. The epidermis serves several functions: protection against water loss, regulation of gas exchange, secretion of metabolic compounds, and (in some species) absorption of water. Most leaves show dorsoventral anatomy: the upper (adaxial) and lower (abaxial) surfaces have somewhat different construction and may serve different functions. The epidermis is usually transparent (epidermal cells lack chloroplasts) and coated on the outer side with a waxy cuticle that prevents water loss. The cuticle may be thinner on the lower epidermis than on the upper epidermis; and is thicker on leaves from dry climates as compared with those from wet climates. The epidermis tissue includes several differentiated cell types: epidermal cells, guard cells, subsidiary cells, and epidermal hairs (trichomes). The epidermal cells are the most numerous, largest, and least specialized. These are typically more elongated in the leaves of monocots than in those of dicots. The epidermis is covered with pores called stomata (sing., stoma), part of a stoma complex consisting of a pore surrounded on each side by chloroplast-containing guard cells, and two to four subsidiary cells that lack chloroplasts. The stoma complex regulates the exchange of gases and water vapor between the outside air and the interior of the leaf. Typically, the stomata are more numerous over the abaxial (lower) epidermis than the (adaxial) upper epidermis. Trichomes or hairs grow out from the epidermis in many species.

Mesophyll

Most of the interior of the leaf between the upper and lower layers of epidermis is a parenchyma (ground tissue) or chlorenchyma tissue called the mesophyll (= middle leaf). This "assimilation tissue" is the primary location of photosynthesis in the plant. The products of photosynthesis are called assimilates. In ferns and most flowering plants the mesophyll is divided into two layers:
- An upper palisade layer of tightly packed, vertically elongated cells, one to two cells thick, directly beneath the adaxial epidermis. Its cells contain many more chloroplasts than the spongy layer. These long cylindrical cells are regularly arranged in one to five rows. Cylindrical cells, with the chloroplasts close to the walls of the cell, can take optimal advantage of light. The slight separation of the cells provides maximum absorption of carbon dioxide. This separation must be minimal to afford capillary action for water distribution. In order to adapt to their different environment (such as sun or shade), plants had to adapt this structure to obtain optimal result. Sun leaves have a multi-layered palisade layer, while shade leaves or older leaves closer to the soil, are single-layered.
- Beneath the palisade layer is the spongy layer. The cells of the spongy layer are more rounded and not so tightly packed. There are large intercellular air spaces. These cells contain less chloroplasts than those of the palisade layer. The pores or stomata of the epidermis open into substomatal chambers, connecting to air spaces between the spongy layer cells. These two different layers of the mesophyll are absent in many aquatic and marsh plants. Even an epidermis and a mesophyll may be lacking. Instead for their gaseous exchanges they use a homogenous aerenchyma (thin-walled cells separated by large gas-filled spaces). Their stomata are situated at the upper surface. Leaves are normally green in color, which comes from chlorophyll found in plastids in the chlorenchyma cells. Plants that lack chlorophyll cannot photosynthesize. Leaves in temperate, boreal, and seasonally dry zones may be seasonally deciduous (falling off or dying for the inclement season). This mechanism to shed leaves is called abscission. After the leaf is shed, a leaf scar develops on the twig. In cold autumns they sometimes turn yellow, bright orange or red as various accessory pigments (carotenoids and anthocyanins) are revealed when the tree responds to cold and reduced sunlight by curtailing chlorophyll production.

Veins

The veins are the vascular tissue of the leaf and are located in the spongy layer of the mesophyll. They are typical examples of pattern formation through ramification. The veins are made up of:
- xylem, which brings water from the stem into the leaf.
- phloem, which usually moves sap out, the latter containing the glucose produced by photosynthesis in the leaf. The xylem typically lies over the phloem. Both are embedded in a dense parenchyma tissue (= ground tissue), called pith, with usually some structural collenchyma tissue present.

Leaf morphology

External leaf characteristics (such as shape, margin, hairs, etc.) are important for identifying plant species, and botanists have developed a rich terminology for describing leaf characteristics. phloem Leaves may be classified in many different ways, and the type is usually characteristic of a species, although some species produce more than one type of leaf. The terminology associated with describing leaf morphology is presented (with illustrations) at [http://wikibooks.org/wiki/Botany:_Leaves_(forms) Wikibooks].

Basic leaf types

- Ferns have fronds.
- Conifer leaves are typically needle-, awl-, or scale-shaped
- Angiosperm (flowering plant) leaves: the standard form includes stipules, petiole, and lamina.
- Microphyll leaves.
- Sheath leaves (type found in most grasses).
- Other specialized leaves.

Arrangement on the stem

As a stem grows, leaves tend to appear arranged around the stem in away that optimizes yield of light. In essence, leaves come off the stem in a spiral pattern, either clockwise or counterclockwise, with (depending upon the species) the same angle of divergence. There is a regularity in these angles and they follow the numbers in a Fibonacci series: 1/2, 2/3, 3/5, 5/8, 8/13, 13/21, 21/34, 34/55, 55/89. This series tends to a limit of 360° x 34/89 = 137,52 or 137° 30', an angle known mathematically as the 'golden angle'. In the series, the numerator gives the number of complete turns or gyres until the leaf arrives at the initial position. The denominator gives the number of leaves in the arrangement. This can be demonstrated by the following:
- alternate leaves have an angle of 180° (or 1/2)
- 120° (or 1/3) : three leaves in one circle
- 144° (or 2/5) : five leaves in two gyres
- 135° (or 3/8) : eight leaves in three gyres. The fact that an arrangement of anything in nature can be described by a mathematical formula is not in itself mysterious. Mathematics is the science of discovering numerical relationships and applying formulae to these relationships. The formulae themselves can provide clues to the underlying physiological processes that, in this case, determine where the next leaf bud will form in the elongating stem. However, we can more easily describe the arrangement of leaves using the following terms:
- Alternate — leaf attachments singular at nodes, and leaves alternate direction, to a greater or lesser degree, along the stem.
- Opposite — leaf attachments paired at each node; decussate if, as typical, each successive pair is rotated 90° going along the stem; or distichous if not rotated, but two-ranked (in the same plane).
- Whorled — three or more leaves attach at each point or node on the stem. As with opposite leaves, successive whorls may or may not be decussate, rotated by half the angle between the leaves in the whorl (i.e., successive whorls of three rotated 60°, whorls of four rotated 45°, etc). Note: opposite leaves may appear whorled near the tip of the stem.
- Rosulate — leaves form a rosette ( = a cluster of leaves growing in crowded circles from a common center). Fibonacci series

Divisions of the lamina (blade)

Two basic forms of leaves can be described considering the way the blade is divided. A simple leaf has an undivided blade. However, the leaf shape may be one of lobes, but the gaps between lobes do not reach to the main vein. A compound leaf has a fully subdivided blade, each leaflet of the blade separated along a main or secondary vein. Because each leaflet can appear to be a "simple leaf", it is important to recognize where the petiole occurs to identify a compound leaf. Compound leaves are a characteristic of some families of higher plants, such as the Fabaceae.
- Palmately compound leaves have the leaflets radiating from the end of the petiole, like fingers off the palm of a hand. There is no rachis, e.g. Cannabis (hemp) and Aesculus (buckeyes).
- Pinnately compound leaves have the leaflets arranged along the main or mid-vein (called a rachis in this case).
- odd pinnate: with a terminal leaflet, e.g. Fraxinus (ash).
- even pinnate: lacking a terminal leaflet, e.g. Swietenia (mahogany).
- Bipinnately compound leaves are twice divided: the leaflets are arranged along a secondary vein that is one of several branching off the rachis. Each leaflet is called a pinnule. The pinnules on one secondary vein are called pinna; e.g. Albizia (silk tree).
- trifoliate: a pinnate leaf with just three leaflets, e.g. Trifolium (clover), Laburnum (laburnum).
- pinnatifid: pinnately dissected to the midrib, but with the leaflets not entirely separate, e.g. some Sorbus (whitebeams). ;Characteristics of the petiole:
- Petiolated leaves have a petiole.
- In peltate leaves, the petiole attaches to the blade inside from the blade margin.
- Sessile or clasping leaves do not have a petiole. In sessile leaves the blade attaches directly to the stem. In clasping leaves, the blade partially or wholly surrounds the stem, giving the impression that the shoot grows through the leaf such as in Claytonia perfoliata of the purslane family (Portulacaceae). In some Acacia species, such as the Koa Tree (Acacia koa), the petioles are expanded or broadened and function like leaf blades; these are called phyllodes. There may or may not be normal pinnate leaves at the tip of the phyllode. ;Characteristics of the stipule
- A stipule, present on the leaves of many dicotyledons, is an appendage on each side at the base of the petiole, resembling a small leaf. They may be lasting and not be shed (a stipulate leaf, such as in roses and beans); or be shed as the leaf expands, leaving a stipule scar on the twig (an exstipulate leaf).
- The situation, arrangement, and structure of the stipules is called the stipulation.
- free
- adnate : fused to the petiole base
- ochreate : provided with ochrea, or sheath-formed stipules, e.g. rhubarb,
- encircling the petiole base
- interpetiolar : between the petioles of two opposite leaves.
- intrapetiolar : between the petiole and the subtending stem

Venation (arrangement of the veins)

rhubarb There are two subtypes of venation, craspedodromus (the major veins stretch up to the margin of the leaf) and camptodromous (major veins come close to the margin, but bend before they get to it).
- Feather-veined, reticulate — the veins arise pinnately from a single mid-vein and subdivide into veinlets. These, in turn, form a complicated network. This type of venation is typical for dicotyledons.
- Pinnate-netted, penniribbed, penninerved, penniveined; the leaf has usually one main vein (called the mid-vein), with veinlets, smaller veins branching off laterally, usually somewhat parallel to each other; eg Malus (apples).
- Three main veins originate from the base of the lamina, as in Ceanothus.
- Palmate-netted, palmate-veined, fan-veined; several main veins diverge from near the leaf base where the petiole attaches, and radiate toward the edge of the leaf; e.g. most Acer (maples).
- Parallel-veined, parallel-ribbed, parallel-nerved, penniparallel — veins run parallel most the length of the leaf, from the base to the apex. Commissural veins (small veins) connect the major parallel veins. Typical for most monocotyledons, such as grasses.
- Dichotomous — There are no dominant bundles, with the veins forking regularly by pairs; found in Ginkgo and some pteridophytes.
pteridophyte

Leaf terminology

;Shape See Leaf shape

Margins (edge)

The leaf margin is characteristic for a genus and aids in determining the species.
- entire: even; with a smooth margin; without toothing
- ciliate: fringed with hairs
- crenate: wavy-toothed; dentate with rounded teeth, such as Fagus (beech)
- dentate: toothed, such as Castanea (chestnut)
- coarse-toothed: with large teeth
- glandular toothed: with teeth that bear glands.
- denticulate: finely toothed
- doubly toothed: each tooth bearing smaller teeth, such as Ulmus (elm)
- lobate: indented, with the indentations not reaching to the center, such as many Quercus (oaks)
- palmately lobed: indented with the indentations reaching to the center, such as Humulus (hop).
- serrate: saw-toothed with asymmetrical teeth pointing forward, such as Urtica (nettle)
- serrulate: finely serrate
- sinuate: with deep, wave-like indentations; coarsely crenate, such as many Rumex (docks)
- spiny: with stiff, sharp points, such as some Ilex (hollies) and Cirsium (thistles).

Tip of the leaf

- acuminate: long-pointed, prolonged into a narrow, tapering point in a concave manner.
- acute: ending in a sharp, but not prolonged point
- cuspidate: with a sharp, elongated, rigid tip; tipped with a cusp.
- emarginate: indented, with a shallow notch at the tip.
- mucronate: abruptly tipped with a small short point, as a continuation of the midrib; tipped with a mucro.
- mucronulate: mucronate, but with a smaller spine.
- obcordate: inversely heart-shaped, deeply notched at the top.
- obtuse: rounded or blunt
- truncate: ending abruptly with a flat end, that looks cut off.

Base of the leaf

- acuminate: coming to a sharp, narrow, prolonged point.
- acute: coming to a sharp, but not prolonged point.
- auriculate: ear-shaped
- cordate: heart-shaped with the norch away from the stem.
- cuneate: wedge-shaped.
- hastate: shaped like an halberd and with the basal lobes pointing outward.
- oblique: slanting.
- reniform: kidney-shaped but rounder and broader than long.
- rounded: curving shape.
- sagittate: shaped like an arrowhead and with the acute basal lobes pointing downward.
- truncate: ending abruptly with a flat end, that looks cut off.

Surface of the leaf

The surface of a leaf can be described by several botanical terms:
- farinose: bearing farina; mealy, covered with a waxy, whitish powder.
- glabrous: smooth, not hairy.
- glaucous: with a whitish bloom; covered with a very fine, bluish-white powder.
- glutinous: sticky, viscid.
- papillate, papillose: bearing papillae (minute, nipple-shaped protuberances).
- pubescent: covered with erect hairs (especially soft and short ones)
- punctate: marked with dots; dotted with depressions or with translucent glands or colored dots.
- rugose: deeply wrinkled; with veins clearly visible.
- scurfy: covered with tiny, broad scalelike particles.
- tuberculate: covered with tubercles; covered with warty prominences.
- verrucose: warted, with warty outgrowths.
- viscid, viscous: covered with thick, sticky secretions.

Hairiness (trichomes)

Leaves can show several degrees of hairiness. The meaning of several of the following terms can overlap. See also : Trichome.
- glabrous: no hairs of any kind present.
- arachnoid, arachnose: with many fine, entangled hairs giving a cobwebby appearance.
- barbellate: with finely barbed hairs (barbellae).
- bearded: with long, stiff hairs.
- bristly: with stiff hair-like prickles.
- canescent: hoary with dense grayish-white pubescence.
- ciliate: marginally fringed with short hairs (cilia).
- ciliolate: minutely ciliate.
- floccose: with flocks of soft, woolly hairs, which tend to rub off.
- glandular: with a gland at the tip of the hair.
- hirsute: with rather rough or stiff hairs.
- hispid: with rigid, bristly hairs.
- hispidulous: minutely hispid.
- hoary: with a fine, close grayish-white pubescence.
- lanate, lanose: with woolly hairs.
- pilose: with soft, clearly separated hairs.
- puberulent, puberulous: with fine, minute hairs.
- pubescent: with soft, short and erect hairs.
- scabrous, scabrid: rough to the touch
- sericeous: silky appearance through fine, straight and appressed (lying close and flat) hairs.
- silky: with adpressed, soft and straight pubescence.
- stellate, stelliform: with star-shaped hairs.
- strigose: with appressed, sharp, straight and stiff hairs.
- tomentose: densely pubescent with matted, soft white woolly hairs.
- cano-tomentose: between canescent and tomentose
- felted-tomentose: woolly and matted with curly hairs.
- villous: with long and soft hairs, usually curved.
- woolly: with long, soft and tortuous or matted hairs.

Adaptations

In order to survive in a harsh environment, leaves can adapt in the following ways:
- Hairs develop on the leaf surface to trap humidity in dry climates, creating a large boundary layer to lessen water loss
- Leaves rustle to move humidity away from the surface reducing the boundary layer resistance between the leaf and the air.
- Plant prickles are modified clusters of epidermal hairs
- Waxy leaf surfaces form to prevent water loss
- Small, shiny leaves to deflect the sun's rays
- Thicker leaves to store water (e.g. rhubarb)
- Change to spines instead of laminar (blade) leaves (e.g. cactus)
- Shrink (to phyllodes) or disappear (with the appearance of cladodes), as photosynthetic functions are transferred to the leaf stem (Acacia species)
- Change shape to deflect wind or reduce wind resistance
- Leaves to trap insects (e.g. pitcher plant)
- Change to bulb parts to store food (e.g. onion)
- Produce aromatic oils to deter herbivores (e.g. eucalypts)
- Protect as spines, which are modified leaves.

External links

- [http://www.ibiblio.org/botnet/glossary/b_i.html Position and Arrangement] Category:Photosynthesis Category:Plant physiology Category:plant morphology Category:Plant anatomy ko:잎 ja:葉 th:ใบไม้

Flower

Flower anatomy

Floral formula

Flower function

Flowers in gardening and horticulture

Main and related articles at: Gardening, Horticulture, List of flowers, and Flower album Flower album

Flowers in the arts

Flowers in everyday life

Flowers as symbols

References

- Eames, A. J. 1961. Morphology of the Angiosperms. McGraw-Hill Book Co., New York.

External links

Sepal

A sepal is a tepal (a segment) of the calyx of a flower. The calyx is the outer part of the perianth, which comprises the sterile inner and outer tepals that are usually differentiated into petals and sepals. The term tepal is usually applied when the petals and sepals are not differentiated. However, in a "typical" flower the sepals are green and lie under the more conspicuous petals. When the flower is in bud, the sepals enclose and protect the more delicate floral parts within. The number of sepals in a flower (called merosity) is indicative of the plant's classification: eudicots having typically four or five sepals and monocots and palaeodicots having three, or some multiple of three, sepals. There exists considerable variation in form of the sepals among the flowering plants. Often the sepals are much reduced, appearing somewhat awn-like, or as scales, teeth, or ridges. Examples of flowers with much reduced perianths are found among the grasses. In some flowers, the sepals are fused towards the base, forming a calyx tube. This floral tube can include the petals and the attachment point of the stamens. Category: Plant morphology

Stamen

]] The stamen is the male organ of a flower. Each stamen generally has a stalk called the filament, and, on top of the filament, an anther. The anther is usually composed of four pollen sacs, which are called microsporangia. The development of the microsporangia and the contained haploid spores (called pollen-grains) is closely comparable with that of the microsporangia in gymnosperms or heterosporous ferns. The pollen is set free by the opening (dehiscence) of the anther, generally by means of longitudinal slits, but sometimes by pores, as in the heath family (Ericaceae), or by valves, as in the barberry family (Berberidaceae). It is then dropped, or carried by some external agent — wind, water or some member of the animal kingdom — onto the receptive surface of the carpel of the same or another flower, which is thus pollinated. Typical flowers have six stamens inside a perianth (the petals and sepals together), arranged in a whorl around the carpel (pistil). But in some species there are many more than six present in a flower (see, for example, the spider tree flower, below). Collectively, the stamens are called an androecium (from Greek andros oikia: man's house). They are positioned just below the gynoecium. The anthers are bilocular, i.e. they have two locules. Each locule contains a microsporangium. The tissue between the locules and the cells is called the connective. In an immature, unopened flower bud, the filaments are still short. Their function is then to transport nutrients to the developing pollen. They start to lengthen once the bud opens. The anther can be attached to the filament in two ways:
- basifixed : attached at its base to the filament; this gives rise to a longitudinal dehiscence (opening along its length to release pollen)
- versatile : attached at its center to the filament; pollen is then released through pores (poricidal dehiscence). nutrient Stamens can be connate (fused or joined in the same whorl):
- monadelphous : fused into a single, compound structure
- diadelphous : joined partially into two androecial structures
- synantherous : only the anthers are connate (such as in the Asteraceae) Stamens can also be adnate (fused or joined from more than one whorl):
- epipetalous : adnate to the corolla
- didynamous : occurring in two pairs of different length
- tetradynamos : occurring as a set of six filaments with two shorter ones
- exserted : extending beyond the corolla
- included : not extending from the corolla.

Plant sexuality

:Main article: Plant sexuality In the typical flower (that is, the majority of flowering plant species) each flower has both a pistil and stamens. Bisexual plants are called hermaphrodites or perfect flowers. In some species, however, the flowers are unisexual with only either male or female parts (monoecious = on the same plant; dioecious = on different plants). A flower with only male reproductive parts is called androecious. A flower with only female reproductive parts is called gynoecious. A flower having only functional stamens is called a staminate flower. An abortive or rudimentary stamen is called a staminodium, such as in Scrophularia nodosa. The pistil and the stamens of orchids are fused into a column. The top part of the column is formed by the anther. This is covered by an anther cap. Image:Crateva_religiosa.jpg|Flower of the spider tree (Crateva religiosa) with its numerous conspicuous stamens Image:WheatFlower3.JPG|Flowers of wheat at anthesis showing stamens. Like all grasses (Poaceae), wheat is wind-pollinated Image:Daylily Stamens dry 01v2.jpg|Stamens of a daylily (Hemerocallis), thickly covered in pollen Image:Albizia_julibrissin_'Rosea'_flower_detail.jpg|Flowers of the "silk tree" (Albizia julibrissin) have many long thread-like stamens

References

- Category:Plant anatomy Category: plant morphology Category:Reproductive system

Carpel

:Not to be confused with carpal, a wrist-bone. carpal A carpel is the female reproductive organ of a flower; the basic unit of the gynoecium. The parts of the carpel are:
- the stigma (plural: stigmas), usually the terminal (end) portion that has no epidermis and is fitted to receive pollen (male gametes); it is commonly somewhat glutinous or viscid;
- the style, a stalk connecting the stigma with the ovary below containing the transmitting tract, which facilitates the movement of the male gamete to the ovule; and
- the ovary (also also called a megasporophyll) containing the female reproductive cell or ovule. The carpel (if single) or carpels (if fused) comprise the pistil of the flower. A flower with two or more fused carpels (called a compound ovary or compound pistil) is termed syncarpous. However, if the gynoecium consists of more than one distinct carpel, it will have more than one pistil and is then termed apocarpous. Apocarpous also pertains to any flower with a single carpel. Fertilization of the ovule or ovules results in development of the carpel(s) into a fruit. fruit The gynoecium is the innermost whorl of the parts of a flower, and in many flowers the other parts (sepals, petals, and stamens) are attached to the receptacle beneath the gynoecium. In such cases, where the ovary lies above the attachments of the other distinct floral parts, the flower is described as hypogynous or as having a superior ovary. In some species (examples include plum, cherry, and blackberry), the other (noncarpellary) floral parts are fused to form a cup called a floral tube or calyx tube. In these flowers, the ovary lies physically lower than the lobes of the sepals and petals and below the point of attachment of the stamen filaments — the ovary is still considered to be superior but the flower is termed perigynous. In those flowers in which the floral tube is fused with the ovary, the sepals, petals, and stamens appear to grow out from the top of the ovary, and the flower is said to be epigynous and have an inferior ovary. Examples of plant families with inferior ovaries include orchid, sunflower, and cactus. The position of the ovary is an important consideration in the identification and classification of plant species, as well as the kind of fruit that develops after fertilization.

Carpel anatomy

The carpel of a simple apocarpous gynoecium appears as a folded structure, differentiated into a basal fertile part (ovary) and an upper sterile part (style). Various interpretations of the origin from a leaf-like structure have been made (Esau, 1965), but the important anatomical description is that of a variously folded tissue surrounding a cavity (called a locule) within which projects one or more ovules, attached by or along a placenta. Typically, a carpel has two placentae. An example of a simple carpel is that of a pea, bean or Arabidopsis: the fruit develops from the single carpel consisting of two rows of ovules aligned beside one another along the placental margin. The union of two or more carpels (syncarpy) may be observable as part of the ontogeny (flower development) or the compound pistil may simply develop as a unit structure (a congenitally fused pistil) to be interpreted as an aspect of the phylogeny (evolutionary history). In a compound pistil, the carpels are fused together in one of two basic ways:
- the carpels are fused at or near their margins (parietal placentation), usually forming a single large cavity — an example would be the violet.
- the folded carpels extend in towards the center, being fused along their outer faces (laterally concrescent), with the placentae arranged around a central column of tissue (axile placentation). There may be as many locules as there are carpels; and tissue of the receptacle may be involved in forming the axillary column. An example of axile placentation would be the lily. A complicating factor in all of this is the fact that in some species syncarpy is present only at the base of the carpels, the pistil being apocarpous in the upper part. The manner of fusing of the carpels can also vary from one part of the pistil to another.

The ovule

The ovule, which represents the megasporangium, when mature, consists of one or two coats surrounding the central nucellus, except at the apex where an opening, the micropyle, is left. The nucellus is a cellular tissue enveloping one large cell, the embryo-sac or megaspore. The germination of the megaspore consists in the repeated division of its nucleus to form two groups of four, one group at each end of the embryo-sac. One nucleus from each group, the polar nucleus, passes to the centre of the sac, where the two fuse to form the so-called definitive nucleus. Of the three cells at the micropylar end of the sac, all naked cells (the so-called egg-apparatus), one is the egg-cell or oosphere, the other two, which may be regarded as representing abortive egg-cells (in rare cases capable of fertilization), are known as synergidae. The three cells at the opposite end are known as antipodal cells and become invested with a cell-wall.

Miscellaneous

The spice saffron is taken from the stigma of the saffron crocus, Crocus sativus.

References

- Esau, K. 1965. Plant Anatomy, 2nd Edition. John Wiley & Sons. 767 pp.
- Category:Plant anatomy Category: plant morphology

Monocotyledon

Base Monocots:

- Acorus
- Alismatales
- Asparagales
- Dioscoreales
- Liliales
- Pandanales
- Family Petrosaviaceae Commelinids:

- Arecales
- Commelinales
- Poales
- Zingiberales
- Family Dasypogonaceae The Monocotyledons or monocots are an extremely important group of flowering plants, dominating great parts of the earth and with many economically important plants. The largest monocot family is the Orchidaceae (orchids), with very complex (and striking) flowers, for highly specific insect pollination. The second largest and perhaps more notable family, the Poaceae or Gramineae (true grasses), have evolved in another direction, becoming highly specialized for wind pollination. Grasses produce small flowers, which may be gathered in highly visible plumes (inflorescences).

Name, characters

The traditional scientific name for this group is Monocotyledones, although recently, e.g. in the Cronquist system, it has been called Liliopsida (class, based on Lilium). As the monocots are a group above the rank of family there is a free choice of name; Article 16 of the ICBN allows either a descriptive name or a name based on a generic name. The traditional name Monocotyledones (some prefer Monocotyledoneae) derives from the fact that most members of this group have one cotyledon, or embryonic leaf, in their seeds. This as opposed to the (traditional) Dicotyledones which typically have two cotyledons. From a diagnostic point of view the number of cotyledons is neither a particularly handy nor reliable character. Nevertheless, monocots are a distinctive group. One of the most noticeable traits is that a monocot's flower is trimerous, with the flower parts in threes or in multiples of three. For example, a monocot's flower could have three, six, or nine petals. Many monocots also have leaves with parallel veins.

Compared to the former Dicotyledons

The schoolbooks have told generations of people that monocotyledons differ from the rest of the flowering plants (formerly named "dicotyledons") as stated below. Obviously that was only a broad sketch, not be taken literally: Seeds: The embryo of the monocot has one cotyledon while the embryo of the dicot has two. Flowers: The flower parts in monocots are multiples of three while in dicots are multiples of four or five. Stems: In monocots, the stem vascular bundles are scattered, while in dicots they are in a ring. Pollen: In monocots, pollen has one furrow or pore while in dicots they have three. Roots: The roots are adventitious in monocots, while in dicots they develop from the radicle. Leaves: In monocots, the major leaf veins are parallel, while in dicots they are reticulated.

Taxonomy

The monocots are considered to form a monophyletic group arising early in the history of the flowering plants. The earliest fossils presumed to be monocot remains date from the early Cretaceous period. The APG II classification System, developed by the Angiosperm Phylogeny Group, recognises "monocots" as one of the two biggest groups in the Angiosperms (flowering plants), the other being the "eudicots", the remnant sometimes being called the "palaeodicots". Within the monocots, the APG II system recognizes ten orders of monocots and two families not yet assigned to any order, and divides these among the Base Monocots and Commelinids:
- Base Monocots
- Family Petrosaviaceae
- Acorales
- Alismatales
- Asparagales
- Dioscoreales
- Liliales
- Pandanales
- Commelinids
- Family Dasypogonaceae
- Arecales
- Commelinales
- Poales
- Zingiberales

References and external links

- Chase MW, Soltis DE, Soltis PS, Rudall PJ, Fay MF, Hahn WJ, Sullivan S, Joseph J, Molvray M, Kores PJ, Givnish TJ, Sytsma KJ, Pires JC (2000). Higher-level systematics of the monocotyledons: An assessment of current knowledge and a new classification. In: Wilson KL, Morrison DA, eds. Monocots: Systematics and Evolution.. CSIRO, Melbourne. 3-16. ISBN 0643064370
- [http://tolweb.org/tree?group=Monocotyledons&contgroup=Euangiosperms Tree of Life Web Project: Monocotyledons] Category: botanical nomenclature category: plant taxonomy ko:외떡잎식물 ja:単子葉植物 th:พืชใบเลี้ยงเดี่ยว

Plant sexuality

Plant sexuality deals with the wide variety of sexual reproduction systems found across the plant kingdom. That plants employ many different strategies to engage in sexual reproduction was used, from just a structural perspective, by Carolus Linnaeus (1735) to propose a system of classification of flowering plants, and later this subject received attention from Charles Darwin (1877). Flowers, the reproductive organs of angiosperms, are more varied than the equivalent structures of any other group of organisms, and flowering plants also have an unrivalled diversity of sexual systems (Barrett, 2002). But sexuality and the significance of sexual reproductive strategies is no less important in all of the other plant groups. The breeding system is the single most important determinant of the mating structure of nonclonal plant populations. The mating structure in turn controls the amount and distribution of genetic variation, a central element in the evolutionary process (Costich, 1995).

Terminology

The complexity of the systems and devices used by plants to achieve sexual reproduction has resulted in botanists and evolutionary biologists proposing numerous terms to describe structures and strategies. Dellaporta and Calderon-Urrea (1993) list and define a variety of terms used to describe the modes of sexuality at different levels in flowering plants. This list is reproduced here (taken from Molner, 2004), generalized to fit more than just plants that have flowers, and expanded to include other terms and better definitions. flower
- Individual sexual organ (a flower in angiosperms):
- Bisexual - Reproductive organ with both male and female equivalent parts (stamens and pistil in angiosperms; also called a perfect flower); another term widely used is hermaphrodite.
- Unisexual - Reproductive structure that is either functionally male or functionally female. In angiosperms this condition is also called imperfect.
- Individual plant:
- Hermaphrodite - A plant that has only hermaphrodite reproductive structures. In angiosperm terminology a synonym is monoclinous from the Greek "one bed".
- Monoecious - having unisexual flowers, conifer cones, or functionally equivalent structures of both sexes appearing on the same plant; from Greek for "one household".
- Dioecious - having unisexual flowers, conifer cones, or functionally equivalent structures occurring on different individuals; from Greek for "two households".
- Because many dioecious conifers show a tendency towards monoecy (that is, a female plant may sometimes produce small numbers of male cones or vice versa), these species are termed subdioecious (McCormick & Andresen, 1963).
- In angiosperm terminology, diclinous ("two beds") includes all species with unisexual flowers, although particularly those with only unisexual flowers, i.e. the monoecious and dioecious species.
- Gynoecious - has only female reproductive structures; the "female" plant.
- Androecious - has only male reproductive structures; the "male" plant.
- Gynomonoecious - has both hermaphrodite and female structures.
- Andromonoecious - has both hermaphrodite and male structures.
- Trimonoecious (polygamous) - male, female, and hermaphrodite structures all appear on the same plant. conifers with pollen and reduced, sterile stigma; (below) shoot with flowers from female plant; (lower right) female flower enlarged, showing stigma
and reduced, sterile stamens with no pollen]]
- Plant population
- Hermaphrodite - only hermaphrodite plants.
- Monoecious - only monoecious plants.
- Dioecious - only dioecious plants.
- Gynodioecious - both female and hermaphrodite plants present.
- Androdioecious - both male and hermaphrodite plants present.
- Trioecious (or subdioecious) - male, female, and hermaphrodite plants are all in the same population.

Morphological mechanisms

Flower morphology

A species, such as the ash (Fraxinus excelsior L.), demonstrates the possible range of variation in morphology and functionality exhibited by flowers with respect to gender. Flowers of the ash are wind-pollinated and lack petals and sepals. Structurally, the flowers may be either male, female, or hermaphrodite, the latter consisting of two anthers and an ovary ('c' below). A male flower can be morphologically male ('a' below) or a hermaphrodite flower with anthers and a rudimentary gynoecium ('b' below; functionally 'male'). Ash flowers can also be morphologically female ('e' below) or hermaphrodite and functionally female ('d' below; with vestigial anthers). 140px 150px 170px 80px 80px (Illustration from Binggeli and Power, 1999)

Physiological mechanisms

- See also: Self-incompatibility in plants, Dichogamy

Evolution

Angiosperms

It is thought that flowering plants evolved from a common hermaphrodite ancestor, and that dioecy evolved from hermaphroditism. Hermaphroditism is very common in flowering plants—about 70% are hermaphroditic, while only about 5% are dioecious and 7% are monoecious. About 7% of species exhibit gynodioecy or androdioecy, while 10% contain both unisexual and bisexual flowers (Molner, 2004). A fair degree of correlation (though far from complete) exists between dioecy/sub-dioecy and plants that have seeds dispersed by birds (both nuts and berries). It is hypothesized that the concentration of fruit in half of the plants increases dispersal efficiency; female plants can produce a higher density of fruit as they do not expend resources on pollen production, and the dispersal agents (birds) need not waste time looking for fruit on male plants.

Cultivation of dioecious plants

Cannabis is famous for being dioecious, with only the female plant desirable for psychotropic effects. It is an interesting plant from a cultivational perspective because while the males are generally separated to prevent pollination of the female plants (undesirable for various reasons), the pheromones produced by the males cause the females to produce more tetrahydrocannabinol, making their unfertilized buds more potent. Experienced growers therefore learn to keep males near enough to the females to have this effect, but far enough that fertilization is unlikely. (Though obviously some females are allowed to be fertilized in order obtain seeds with which to re-populate the crop.)

External link

- [http://waynesword.palomar.edu/ww0404.htm Plant sexuality and political correctness], vol. 4(4) (Winter 1996) at Wayne's Word.

References

- Barrett, S.C.H. 2002. The evolution of plant sexual diversity. Nature Reviews Genetics 3(4): 274-284.
- Binggeli, P. and J. Power. 1999. [http://members.lycos.co.uk/WoodyPlantEcology/species/ash.htm Gender variation in ash (Fraxinus excelsior L.)]
- Costich, D. E. 1995. Gender specialization across a climatic gradient: experimental comparison of monoecious and dioecious Ecballium. Ecology, June 1995.
- Darwin, C. 1877. The Different Forms of Flowers on Plants of the Same Species.
- Dellaporta, S.L. and A. Calderon-Urrea. 1993. Sex determination in flowering plants. The Plant Cell, 5: 1241-1251
- Linnaeus, C. 1735. Systema Naturae.
- McCormick, J. & J. W. Andresen. 1963. A subdioecious population of Pinus cembroides in southeast Arizona. Ohio J. Science, 63: 159-163.
- Molnar, Sebastian. 2004. [http://www.geocities.com/we_evolve/Plants/breeding_sys.html Plant Reproductive Systems], internet version posted February 17, 2004. Category:Botany Category:Sexuality

Dandelion

See text Dandelion (Taraxacum) is a large genus of flowering plants in the family Asteraceae. They are tap-rooted biennial or perennial herbaceous plants, native to temperate areas of the Northern Hemisphere and also temperate southern South America. The genus is taxonomically very complex, with numerous apomictic microspecies, and polyploidy is also common; over 250 species have been recorded in the British Isles alone (Richards 1972). Some botanists take a much broader viewpoint, and only accept a total of about 60 species. British Isles The leaves are 5-25 cm long, simple and basal, entire or lobed, forming a rosette above the central taproot. As the leaves grow outward they push down the surrounding vegetation, such as grass in a lawn, killing the vegetation by cutting off the sunlight. A bright yellow flower head (which is open in the daytime but closes at night) is borne singly on a hollow stem (scape) which rises 4-30 cm above the leaves and exudes a milky sap (latex) when broken. A rosette may produce several flowering stems at a time. The flower head is 2-5 cm in diameter and consists entirely of ray florets; it matures into a globe of fine filaments that are usually distributed by wind, carrying away the seed-containing achenes. This globe (receptacle) is called the "dandelion clock", and blowing it apart is a popular pastime for children. The flower head is surrounded by bracts (sometimes mistakenly called sepals) in two series. The inner bracts are erect until the seeds mature, then flex down to allow the seeds to disperse; the outer bracts are always reflexed downward. Some species drop the "parachute" (called a pappus, modified sepals) from the achenes. Between the pappus and the achene, there is a stalk called beak, which elongates as the fruit matures. The beak breaks off from the achene quite easily. The name dandelion is a derivation of the Old French, dent-de-lion, literally "lion's tooth" on account of the sharply lobed leaves of the plant. In modern French the plant is called pissenlit, "urinate in bed", referring to its diuretic properties. Likewise, "pissabeds" is an English folkname for this plant and "piscialletto" in Italian. ;Species
- Taraxacum officinale (syn. T. vulgare), Common Dandelion. Found in many forms, but differs at least from the following species:
- Taraxacum albidum, a white-flowering Japanese dandelion.
- Taraxacum japonicum, Japanese dandelion. No ring of smallish, downward-turned leaves under the flowerhead.
- Taraxacum laevigatum (syn. T. erythrospermum), Red-seeded Dandelion; achenes reddish brown and leaves deeply cut throughout length. Inner bracts' tips are hooded.
- and others. Japan Dandelions are so similar to catsears (Hypochoeris) that catsears are also known as "false dandelions". Both plants carry similar flowers which form into windborne seeds. However, catsear flowering stems are forked and solid, whereas dandelions possess unforked stems that are hollow. Both plants have a rosette of leaves and a central taproot. However, the leaves of dandelions are jagged in appearance, whereas those of catsear are more lobe-shaped and hairy. Other plants with similar flowers include hawkweeds (Hieracium) and hawksbeards (Crepis); these are readily distinguished by their branched flowering stems. Dandelions are used as food plants by the larvae of some species of Lepidoptera - see list of Lepidoptera which feed on Dandelions.

Cultivation and uses

Away from their native regions, they have become established in Australia and New Zealand as weeds. They are now common plants throughout all temperate regions. weed weed While the dandelion is considered a weed by many gardeners, the plant does have several culinary and medicinal uses. Dandelions are grown commercially at a small scale as a leaf vegetable. The plant can be eaten cooked or raw in various forms, such as in soup or salad. They are probably closest in character to mustard greens. Usually the young leaves and unopened buds are eaten raw in salads, while older leaves are cooked. Raw leaves have a slightly bitter taste. Dandelion salad is often accompanied with hard boiled eggs. Dandelion flowers can be used to make dandelion wine. The leaves are high in vitamin A, vitamin C and iron, containing more iron than spinach. Ground roasted dandelion root can be used as a coffee substitute. Drunk before meals, it is believed to stimulate digestive functions. Sold in most health food stores, often in a mixture, it is considered an excellent cleansing tonic for the liver. Dandelion root is a registered drug in Canada, sold as a diuretic. A leaf decoction can be drunk to "purify the blood", for the treatment of anemia, jaundice, and also for nervousness. The milky latex has been used as a mosquito repellent; the milk is also applied to warts, helping get rid of them without damaging the surrounding skin. A dye can also be obtained from the roots of the plant. "Dandelion and Burdock" is a soft drink that has long been popular in the United Kingdom, and authentic recipes are sold by health food shops, but it is not clear whether the cheaper supermarket versions actually contain either plant.

References and external links

- Richards, A. J. 1972. The Taraxacum flora of the British Isles. Watsonia 9 (supplement): 1-141.
- Gail, Peter. The Dandelion Celebration: A Guide to Unexpected Cuisine. Cleveland, Ohio: Goosefoot Acres Press, 1994. ISBN 1879863510.
- [http://en.wikibooks.org/wiki/Transwiki:How_to_cook_dandelions How to cook dandelions] ~ at Wikibooks
- [http://fohn.net/dandelion-pictures/ Dandelion Poetry, Folklore, Literature, and Pictures]
- [http://www.pfaf.org/database/plants.php?Taraxacum+officinale&CAN=WIKIPEDIA Dandelion at Plants For A Future] Category:Asteraceae Category:Herbs Category:Leaf vegetables Category:Herbal & fungal drugs/medicines Category:Invasive species ja:セイヨウタンポポ

Daisy

Daisy may mean: ;Flowering plants:
- Daisy family, a general name for all species in the family Asteraceae.
- Common Daisy, Bellis species, particularly Bellis perennis.
- Michaelmas Daisy, Aster species.
- Painted Daisy, Tanacetum coccineum.
- Ox-eye Daisy, Leucanthemum species, particularly Leucanthemum vulgare.
- Shasta daisy, Leucanthemum x superbum (formerly Chrysanthemum maximum) is cultivar developed in California (U.S.) and is a perennial growing to a height of 60 - 90 cm. It is apparently a cross between Leucanthemum lacustre from Portugal and L. maximum from the Pyrenees.
- Moon Daisy, Leucanthemopsis species.
- Marguerite Daisy, Argyranthemum frutescens is a perennial plant used in horticulture. It originates from the Canary Islands.
- Crown Daisy or Garland Chrysanthemum, Chrysanthemum coronarium
- "Daisy", Chrysanthemum majus
- Pyrethrum Daisy, Chrysanthemum coccineum
- Tricolor Daisy, Chrysanthemum carinatum ;Places: ;United States:
- Daisy, Arkansas
- Daisy, Georgia ;Other uses:
- DAISY Digital Talking Book
- Daisy chain, a chain made with daisy flowerheads.
- Daisy wheel printer, a printer with the print head shaped like a daisy flowerhead.
- Daisy (television commercial), aired by the Lyndon Johnson campaign in the 1964 presidential election.
- Daisy Bell, a popular song
- A pet name for Margaret or Maggie
- Nickname for actor David Wenham
- Name of the Dagwood Bumstead family dog in Blondie
- Daisy the Dog, set on fire by a neighbor in Fort Worth, Texas in June 2002
- Daisy Duck, a Disney character.
- Princess Daisy, a Nintendo character.
- Daisy-Democracy is Freedom, a moderate centre-left party in Italy.
- Daisy cutter (fuse), a type of fuse used in some bombs.

Family (biology)

In biological classification, family is one of the most important ranks, next only to species and genus. See:
- rank (botany)
- rank (zoology)
- Virus classification rank13 rank13 rank13 als:Familie (Biologie) ms:Famili

Pollination

pollinating a Sedum telephium]] Pollination is an important step in the reproduction of seed plants: the transfer of pollen grains (male gametes) to the plant carpel, the structure that contains the ovule (female gamete). The receptive part of the carpel is called a stigma in the flowers of angiosperms and a micropyle in gymnosperms. The study of pollination brings together many disciplines, such as botany, horticulture, entomology, and ecology. Pollination is important in horticulture because most plant fruits will not develop if the ovules are not fertilised.

Types of pollination

The process of pollination requires pollinators as agents that carry or move the pollen grains from the anther to the receptive part of the carpel. Methods of pollination, categorized by pollinator type, are: anther]
- Entomophily: pollination by insects
- Bee pollination on Sunflower
- Madagascar orchid requires a moth with a 30 cm (1 ft) long proboscis
- Beetles pollinate cycads.
- Zoophily: pollination by animals such as birds or bats
- Hummingbird
- Anemophily: pollination by wind
- very common in grasses
- Sweet chestnut and Tridax
- Conifers
- Hydrophily: pollination by water
- Mesophytes like Ribbonweed Some flowers are pollinated using buzz pollination.

Pollination in agriculture

Pollination management is a branch of horticulture that seeks to protect and enhance present pollinators and often involves the culture and addition of pollinators in monoculture situations, such as commercial fruit orchards. The largest managed pollination event in the world is in Californian almond orchards, where nearly half (about one million hives) of the US honeybees are trucked to the almond orchards each spring. New York's apple crop requires about 30,000 hives; Maine's blueberry crop uses about 50,000 hives each year. Bees are also brought to commercial plantings of cucumbers, squash, melons, strawberries, and many other crops. Honeybees are not the only managed pollinators: other species of bees are also raised as pollinators. The alfalfa leafcutter bee is an important pollinator for alfalfa seed in western United States and Canada. Bumblebees are increasingly raised and used extensively for greenhouse tomatoes and other crops. The ecological and financial importance of natural pollination by insects to agricultural crops, improving their quality and quantity, becomes more and more appreciated and has given rise to new financial opportunities. The vicinity of a forest or wild grasslands near agricultural crops, such as apples, almonds or coffee can improve their yield by about 20%. This may result in forest owners demanding payment for their part in the improved results. This is a simple example of the economic value of ecological services. Pollination also requires consideration of pollenizers. (The terms "pollinator" and "pollenizer" are often confused: a pollinator is the agent that moves the pollen, whether it be wind, bees, bats, moths, or birds; a pollenizer is the plant that provides the pollen.) Some plants are self-fertile or self-compatible and can pollinate themselves. Other plants have chemical or physical barriers to self-pollination and need to be cross-pollinated: with these self-infertile plants, not only pollinators must be considered but pollenizers as well. In pollination management, a good pollenizer is a plant that provides compatible, viable and plentiful pollen and blooms at the same time as the plant that is to be pollinated. Pollination can be cross-pollination with a pollinator and an external pollenizer, self-pollenization with a pollinator, or self-pollination without any pollinator:
- Cross-pollination (syngamy): pollen is delivered to a flower of a different plant. Plants adapted to outcross or cross-pollinise have taller stamens than carpels to better spread pollen to other flowers.
- Self-pollenization (autogamy): pollen moves to the female part of the same flower, or to another flower on the same individual plant. This is sometimes referred to as self-pollination, but this is not synonymous with autogamy. Clarity requires that the term "self-pollination" be restricted to those plants that accomplish pollination without an external pollinator (example: the stamens actually grow into contact with the pistil to transfer the pollen). Most peach varieties are autogamous, but not truly self-pollinated, as it is generally an insect pollinator that moves the pollen from anther to stigma. Plants adapted to self-fertilize have similar stamen and carpel length.
- Cleistogamy: pollination that occurs before the flower opens is always self-pollination. Some cleistogamous flowers never open, in contrast to chasmogamous flowers that open and are then pollinated. Cleistogamous flowers must of necessity be self-compatible or self-fertile plants. Other plants are self-incompatible. These are end points on a continuum, not absolute points. Hybridization is effective pollination between flowers of different species of the same genus, or even between flowers of different genera (as in the case of several orchids). Peaches are considered self-fertile because a commercial crop can be produced without cross-pollination, though cross-pollination usually gives a better crop. Apples are considered self-incompatible, because a commercial crop must be cross-pollinated. Remember that most fruits are grafted clones, genetically identical. An orchard block of apples of one variety is in effect all one plant. Growers now consider this a mistake. One means of correcting this mistake is to graft a limb of an appropriate pollenizer (generally a variety of crabapple) every six trees or so. To attract pollinators, some flowers, such as sunflower, when viewed under ultraviolet light (as they would be seen by honeybees), have a darker centre, where the pollen is located. There may also be patterns upon the petals. These are called nectar guides. Pollination of food crops has become an environmental issue, due to two cross trends. The trend to monoculture means that greater concentrations of pollinators are needed at bloom time than ever before, yet the area is forage poor or even deadly to bees for the rest of the season. The other trend is the decline of pollinator populations, due to pesticide misuse and overuse, new diseases and parasites of bees, [clearfelling|[clearcut logging]], decline of beekeeping, suburban development, removal of hedges and other habitat from farms, and public paranoia about bees. Widespread aerial spraying for mosquitoes due to West Nile fears is causing an acceleration of the loss of pollinators. The US solution to the pollinator shortage, so far, has been for commercial beekeepers to become pollination contractors and to migrate. Just as the combine harvesters follow the wheat harvest from Texas to Manitoba, beekeepers follow the bloom from south to north, to provide pollination for many different crops.

Bee pollination

Manitoba structure appears rough and globular to the left. The bee's stash of pollen is on its hindleg]] Bees travel from flower to flower, collecting nectar (later converted to honey), and in the process they pick up pollen grains. The bee collects the pollen by rubbing against the anthers. The pollen collects on the hind legs, in dense hairs referred to as a pollen basket. As the bee flies from flower to flower, the pollen grains are transferred onto the stigma of the female flower part. Nectar provides the energy for bee nutrition; pollen provides the protein. When bees are rearing large quantities of brood (beekeepers say hives are "building"), bees will deliberately gather pollen to meet the nutritional needs of the brood. A honeybee that is deliberately gathering pollen is up to ten times more efficient as a pollinator than one that is primarily gathering nectar and only unintentionally transferring pollen. Good pollination management seeks to have bees in a "building" state during the bloom period of the crop, thus requiring them to gather pollen, and making them more efficient pollinators. Thus the management techniques of a beekeeper providing pollination service are different from, and somewhat incompatible with, those of a beekeeper who is trying to produce honey.

Number of hives needed per acre (4,000 m²) of crop pollination

beekeeper]] :Apples: 1—2 :Blueberries: 4 :Cantaloupe: 2—4 :Cucumber 2—1 :Squash: 1 :Watermelon: 1—3 It is estimated that about one hive per acre will sufficiently pollinate watermelons. In the 1950s when the woods were full of wild bee trees, and beehives were normally kept on most South Carolina farms, a farmer who grew ten acres (40,000 m²) of watermelons would be a large grower and probably had all the pollination needed. But today's grower may grow 200 acres (800,000 m²), and, if lucky, there might be one bee tree left within range. The only option in the current economy is to bring beehives to the field during blossom time. Source: Delaplaine et al. 1994, Bee pollination of Georgia crop plants. CES Bulletin 1106

Wiktionary Entries

- Cross-pollination
- Pollination

External links

- [http://www.beeculture.com/beeculture/book/index.html Insect Pollination Of Cultivated Crop Plants by S. E. McGregor USDA 1972] (needs updating but still valuable)
- [http://pollinator.com The Pollination Home page]
- [http://www.pulseplanet.com/archive/May98/1625.html Pulse of the Planet description of buzz pollination] Category:Biological reproduction Category:Ecology Category:Sexuality Category:Symbiosis Category:Pollination ja:受粉

Bee

Andrenidae
Apidae
Colletidae
Halictidae
Heterogynaidae
Megachilidae
Melittidae
Oxaeidae
Sphecidae
Stenotritidae Bees (Apoidea superfamily) are flying insects, closely related to wasps and ants. They are adapted for feeding on nectar and pollen, the former primarily as an energy source, and the latter primarily for protein and other nutrients. Most pollen is used for food for the brood. Bees have a long proboscis that enables them to obtain the nectar from flowers. Bees have antennae made up of thirteen segments in males and twelve in females. They have two pairs of wings, the back pair being the smaller of the two. Bees play an important role in pollinating flowering plants, and are called pollinators. Bees may focus on gathering nectar or on gathering pollen, depending on their greater need at the time. Bees gathering nectar may accomplish pollination, but bees that are deliberately gathering pollen are more efficient pollinators. It is estimated that one third of the human food supply depends on insect pollination, most of this accomplished by bees. Bees are fuzzy and carry an electrostatic charge, thus aiding in the adherence of pollen. Bees periodically stop foraging and groom themselves to pack the pollen into specialized pollen baskets which are on the legs of honeybees and some other species, and on the ventral abdomen on other species. Bees are extremely important as pollinators in agriculture, with contract pollination having overtaken the role of honey production for beekeepers in many countries. Monoculture and pollinator decline have increasingly caused honeybee keepers to become migratory so that bees can be concentrated in areas of pollination need at the appropriate season. Many other species of bees are increasingly cultured and used to meet agricultural pollination need. Bees also play a major, though not always understood, role in providing food for birds and wildlife. Many of these bees survive in refuge in wild areas away from agricultural spraying, only to be poisoned in massive spray programs for mosquitoes, gypsy moths, or other pest insects. There are over 16,000 described species, and possibly around 30,000 species in total. Many species are poorly known. The smallest bee is a dwarf bee (trigona minima) and it is 1/12 in long. The largest bee in the world is the Megachile pluto.

Eusocial and quasisocial bees

Bees may be solitary, or may live in various sorts of communities. The most advanced of these are eusocial colonies, found among the honeybees and stingless bees. Sociality is believed to have evolved separately in different groups of bees. Eusocial bees live in colonies, each of which has a single queen, together with workers and drones. When humans provide a home for a colony, the structure is called a hive. A hive can typically contain up to about 40,000 individual bees at their annual peak, which occurs in the spring, but usually have fewer. Visiting flowers is a dangerous occupation, with very high mortality rates. Many assassin bugs and crab spiders hide in flowers to capture unwary bees. Others are lost to birds in flight. Insecticides used on blooming plants can kill large numbers of bees, both by direct poisoning and by contaminating their food supply. A honeybee queen may lay 2000 eggs per day during spring buildup, but she also must lay 1000 to 1500 eggs per day during the foraging season, simply to replace daily casualties. Bumblebees (Bombus terrestris, B. pratorum, et al.) are referred to as quasisocial because the queen bee is typically able to survive on her own for at least a short time (unlike queens in eusocial species who must be cared for at all times). Bumblebee colonies typically have from 50 to 200 individual bees at peak population, which occurs in mid to late summer. The population value of bees depends partly on the individual efficiency of the bees, but also on the population. Thus, while bumblebees have been found to be about ten times more efficient pollinators on cucurbits, the total efficiency of a colony of honeybees is much greater, due to greater numbers. Likewise, during early spring orchard blossoms, bumblebee populations are limited to only a few queens, thus they are not significant pollinators of early fruit. Bumblebee] The life cycle of bumblebees begins in the spring when the queen bee rises from hibernation. At this time the queen bee is the one who does all the work as there are no worker bees to do the work yet. She searches for a place to build her nest and she builds the honeypots. She also does the foraging to collect nectar and pollen. Bumblebee colonies die off in the autumn, after raising a last generation of queens, which survive individually. Interestingly bumblebee queens sometimes seek winter safety in honeybee hives, where they are sometimes found dead in the spring by beekeepers, presumably stung to death by the honeybees. It is not known whether any succeed in winter survival in such an environment. With honeybees, which survive winter as a colony, the queen begins egg laying in mid to late winter, to prepare for spring. This is most likely triggered by longer day length. She is the only fertile female, and deposits all the eggs from which the other bees are produced. Except a brief mating period, when she may make several flights to mate with drones or if she leaves in later life with a swarm to establish a new colony, the queen rarely leaves the hive after the larvae have become full grown bees. The queen deposits each egg in a cell prepared by the worker bees. The egg hatches into a small larva which is fed by nurse bees (worker bees who maintain the interior of the colony). After about a week (depending on species), the larva is sealed up in its cell by the nurse bees and begins the pupal stage. After another week (again, depending on species), it will emerge an adult bee. The larvae and pupae in a frame of honeycomb are referred to as frames of brood and are often sold (with adhering bees) by beekeepers to other beekeepers to start new beehives. brood Both workers and queens are fed royal jelly during the first three days of the larval stage. Then workers are switched to a diet of pollen and nectar or diluted honey, while those intended for queens will continue to receive royal jelly. This causes the larva to develop to the pupa stage more quickly, while being also larger and fully developed sexually. Queen breeders consider good nutrition during the larval stage to be of critical importance to the quality of the queens raised, good genetics and sufficient number of matings also being factors. During the larval and pupal stages, various parasites can attack the pupa/larva and destroy or damage it. Queens are not raised in typical horizontal brood cells of the honeycomb. They are specially constructed to be much larger, and have a vertical orientation. As the queen finishes her larval feeding, and pupates, she moves into a head downward position, from which she will later chew her way out of the cell. At pupation the workers cap or seal the cell. Just prior to emerging from their cells, young queens can often be heard "piping." This is considered likely to be a challenge to other queens for battle. honeycomb Worker bees are infertile females. Worker bees secrete the wax used to build the hive, clean and maintain the hive, raise the young, guard the hive and forage for nectar and pollen. In honeybees, the worker bees have a modified ovipositor called a stinger with which they can sting to defend the hive. Contrary to popular belief, the bee will not always die soon after stinging: this is a misconception based on the fact that a bee will always die shortly after stinging a mammal; however, the stinger evolved primarily for inter-bee combat. Drone bees are the male bees of the colony. Drone honeybees do not forage for nectar or pollen. The primary purpose of a drone bee is to fertilize a new queen. Drones mate with the queen in flight. They die immediately after mating. In some species, drones are suspected of playing a contributing role in the temperature regulation of the hive. Drone bees have no stinger, since a stinger is actually a modified ovipositor. Queens live for up to three years, while workers have an average life of only three months (during the foraging season, but longer in places with extended winters). Honeybee queens release pheromones to regulate hive activities, and worker bees also produce pheromones for various communications. pheromone By collecting nectar from flowers, bees produce honey, which is a clear liquid consisting of nearly 80% water with complex sugars. The collecting bees store the nectar in a second stomach and return to the hive where worker bees remove the nectar. The worker bees digest the raw nectar for about 30 minutes using enzymes to break up the complex sugars into simpler ones. Raw honey is then spread out in empty honeycomb cells to dry, which reduces the water content to less than 20%. When nectar is being processed, honeybees create a draft through the hive by fanning with their wings. Once dried, the cells of the honeycomb are sealed (capped) with wax to preserve the honey. Honey itself is so sweet that bacteria cannot grow on it, and dry enough that it does not support yeasts. Anaerobic bacteria may be present and survive in spore form in honey, however, as well as anywhere else in common environments. Honey (or any other sweetener) which is diluted by the non-acidic digestive fluids of infants, can provide an ideal medium for the transition of botulism bacteria from the spore form to the actively growing form, which produces a toxin. When infants are weaned to solid foods, their digestive system becomes acidic enough to prevent such growth and poisoning. No sweeteners should be given to infants prior to weaning, as there is a small but real risk of lethal poisoning.

Honeybee pheromones

Honeybees use special pheromones, or chemical communication, for almost all behaviors of life. Such uses include (but are not limited to): mating, alarm, defense, orientation, kin and colony recognition, food production, and integration of colony activities. Pheromones are thus essential to honeybees for their survival.

Solitary, and communal bees

Other species of bee such as the carpenter bee, Orchard Mason bee (Osmia lignaria) and the hornfaced bee (Osmia cornifrons) are solitary in that every female is fertile. There are no worker bees for these species. Solitary bees typically produce neither honey nor beeswax. They are immune from acarine and varroa mites, but have their own unique parasites, pests and diseases. (See diseases of the honeybee.) Solitary bees are important pollinators, as pollen is gathered for provisioning the nests with food for their brood. Often it is mixed with nectar to form a paste-like consistancey. Many solitary bees have very advanced types of pollen carry structures on their bodies. Most solitary bees are wild, with a few species being increasingly cultured for pollination. Solitary bees are often specialists, in that they only visit one or more species of plant (unlike honeybees and bumblebees which are generalists). In some cases only one species of bee can pollinate a plant species, and some plants are endangered because their pollinator is dying off. Solitary bees create nests in hollow reeds, bored holes in wood, or in tunnels in the ground. The female typically creates a compartment with an egg and some provisions for the resulting larva, then seals it off. A nest may consist of numerous compartments, usually the last (the closest to the entrance) being eggs that will become males. The adult does not care for the brood, and usually dies after making one or more nests. The males emerge first and are ready for mating when the females emerge. Providing nest boxes for solitary bees is increasingly popular for gardeners. Solitary bees are usually stingless or very unlikely to sting. While solitary females each make individual nests, some species are gregarious, preferring to make nests near others of the same species, giving the appearance to the causual observer that they are social.

Kleptoparasitic bees

Cuckoo bees are bumblebee look-alikes that invade bumblebee nests and lay their eggs. The bumblebees raise the young as their own. Megachilid bees also have other megachilid Coelioxys bees whose young are placed into the already provisioned nests of these solitary bees. They destroy the host larvae and eat the food. See also Kleptoparasitism
Communication
:"The general story of the communication of the distance, the situation, and the direction of a food source by the dances of the returning (honeybee) worker bee on the vertical comb of the hive, has been known in general outline from the work of Karl von Frisch in the middle 1950s." The dance involve a returning bee running around in a tight figure of eight dance, waggling its abdomen as it does so. All the other bees gather around, apparently scrutinising the ceremonial manoeuvre.
Miscellaneous
Bees figure more prominently in myth than any other insect. See Bee (mythology). Bees are the favorite meal of Merops apiaster, a bird. Other common predators are kingbirds, mockingbirds, and dragonflies. Bee stings have also been reputed to help alleviate the associated symptoms of Multiple sclerosis, arthritis, and other autoimmune diseases. This is an area of ongoing research. Image:Vanderwoning_bee5515.jpg|Bee Image:Bees-wings.web.jpg|Bees wings Image:Bee mid air.jpg|Bee flying Image:Bee taking off.jpg|Bee Taking off from flowers Image:Bee on dandelion.JPG|A bee on a dandelion Image:Bee flying to almond flower.jpg|Bee flying to almond flower Image:Bee landing on rosemary02.jpg|Bee landing on rosemary bush Image:Bee landing on rosemary.jpg|Bee landing on rosemary bush Image:Rosemary with bee landing02.jpg|Bee landing on rosemary bush
See also

- Africanized bee
- Bee anatomy (mouth)
- Bee learning and communication
- Beekeeping
- Bee sting therapy
- Characteristics of common wasps and bees
- Honeybee
- Honeybee life cycle
- Western honeybee
- Maya the Bee
External links and references

- Bees of the World, C. D. Michener (200)
- [http://www.bwars.com/ Bees, Wasps and Ants Recording Society] (UK)
- [http://gears.tucson.ars.ag.gov Carl Hayden Bee Research Center]
- [http://www.pollinatorparadise.com/ Pollinator Paradise] (solitary bees)
- [http://www.kutikshoney.com/grafting/queens.htm Kutik's Honey Farm] Raising honeybee queens
- [http://www.abc.net.au/science/scribblygum/may2003/default.htm Rescuing Australian stingless bees]
- [http://www.geocities.com/Athens/Olympus/3294/pheromo.htm Honey Bee Pheromones]
- [http://www.sankey.ws/firstbee.html The first bee of spring] Category:Aculeate Hymenoptera Category:Insects Category:Pollination ko:벌 ms:Lebah ja:ハチ simple:Bee

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