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The stamen (
plural The plural (sometimes list of glossing abbreviations, abbreviated pl., pl, or ), in many languages, is one of the values of the grammatical number, grammatical category of number. The plural of a noun typically denotes a quantity greater than the ...
''stamina'' or ''stamens'') is the
pollen Pollen is a powdery substance produced by seed plants. It consists of pollen grains (highly reduced microgametophytes), which produce male gametes (sperm cells). Pollen grains have a hard coat made of sporopollenin that protects the gametop ...
-producing
reproductive organ A sex organ (or reproductive organ) is any part of an animal or plant that is involved in sexual reproduction. The reproductive organs together constitute the reproductive system. In animals, the testis in the male, and the ovary in the female, ...
of a
flower A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to facilitate reproduction, usually by providing a mechanis ...
. Collectively the stamens form the androecium., p. 10


Morphology and terminology

A stamen typically consists of a stalk called the filament and an anther which contains '' microsporangia''. Most commonly anthers are two-lobed and are attached to the filament either at the base or in the middle area of the anther. The sterile tissue between the lobes is called the connective, an extension of the filament containing conducting strands. It can be seen as an extension on the dorsal side of the anther. A pollen grain develops from a
microspore Microspores are land plant spores that develop into male gametophytes, whereas megaspores develop into female gametophytes. The male gametophyte gives rise to sperm cells, which are used for fertilization of an egg cell to form a zygote. Megasp ...
in the microsporangium and contains the male
gametophyte A gametophyte () is one of the two alternating multicellular phases in the life cycles of plants and algae. It is a haploid multicellular organism that develops from a haploid spore that has one set of chromosomes. The gametophyte is the ...
. The stamens in a flower are collectively called the androecium. The androecium can consist of as few as one-half stamen (i.e. a single
locule A locule (plural locules) or loculus (plural loculi) (meaning "little place" in Latin) is a small cavity or compartment within an organ or part of an organism (animal, plant, or fungus). In angiosperms (flowering plants), the term ''locule'' usu ...
) as in '' Canna'' species or as many as 3,482 stamens which have been counted in the saguaro (''Carnegiea gigantea''). The androecium in various species of plants forms a great variety of patterns, some of them highly complex. It generally surrounds the
gynoecium Gynoecium (; ) is most commonly used as a collective term for the parts of a flower that produce ovules and ultimately develop into the fruit and seeds. The gynoecium is the innermost whorl of a flower; it consists of (one or more) '' pist ...
and is surrounded by the
perianth The perianth (perigonium, perigon or perigone in monocots) is the non-reproductive part of the flower, and structure that forms an envelope surrounding the sexual organs, consisting of the calyx (sepals) and the corolla ( petals) or tepals when ...
. A few members of the family Triuridaceae, particularly '' Lacandonia schismatica'' and '' Lacandonia braziliana'', along with a few species of '' Trithuria'' (family Hydatellaceae) are exceptional in that their gynoecia surround their androecia.


Etymology

* Stamen is the
Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through ...
word meaning "thread" (originally thread of the
warp Warp, warped or warping may refer to: Arts and entertainment Books and comics * WaRP Graphics, an alternative comics publisher * ''Warp'' (First Comics), comic book series published by First Comics based on the play ''Warp!'' * Warp (comics), a ...
, in weaving). * Filament derives from
classical Latin Classical Latin is the form of Literary Latin recognized as a literary standard by writers of the late Roman Republic and early Roman Empire. It was used from 75 BC to the 3rd century AD, when it developed into Late Latin. In some later period ...
filum, meaning "thread"Lewis, C.T. & Short, C. (1879). ''A Latin dictionary founded on Andrews' edition of Freund's Latin dictionary.'' Oxford: Clarendon Press. * Anther derives from French anthère,Klein, E. (1971). ''A comprehensive etymological dictionary of the English language. Dealing with the origin of words and their sense development thus illustration the history of civilization and culture.'' Amsterdam: Elsevier Science B.V. from classical Latin anthera, meaning "medicine extracted from the flower"Siebenhaar, F.J. (1850). ''Terminologisches Wörterbuch der medicinischen Wissenschaften.'' (Zweite Auflage). Leipzig: Arnoldische Buchhandlung.Saalfeld, G.A.E.A. (1884). ''Tensaurus Italograecus. Ausführliches historisch-kritisches Wörterbuch der Griechischen Lehn- und Fremdwörter im Lateinischen.'' Wien: Druck und Verlag von Carl Gerold's Sohn, Buchhändler der Kaiserl. Akademie der Wissenschaften. in turn from
Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic pe ...
ἀνθηρά (), feminine of ἀνθηρός () meaning "flowery",Liddell, H.G. & Scott, R. (1940). ''A Greek-English Lexicon. revised and augmented throughout by Sir Henry Stuart Jones. with the assistance of. Roderick McKenzie.'' Oxford: Clarendon Press. from ἄνθος () meaning "flower" * Androecium (plural ''androecia'') derives from
Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic pe ...
ἀνήρ () meaning "man", and οἶκος () meaning "house" or "chamber/room".


Variation in morphology

Depending on the species of plant, some or all of the stamens in a flower may be attached to the petals or to the floral axis. They also may be free-standing or fused to one another in many different ways, including fusion of some but not all stamens. The filaments may be fused and the anthers free, or the filaments free and the anthers fused. Rather than there being two locules, one locule of a stamen may fail to develop, or alternatively the two locules may merge late in development to give a single locule. Extreme cases of stamen fusion occur in some species of '' Cyclanthera'' in the family Cucurbitaceae and in section ''Cyclanthera'' of genus ''
Phyllanthus ''Phyllanthus'' is the largest genus in the plant family Phyllanthaceae. Estimates of the number of species in this genus vary widely, from 750David J. Mabberley. 2008. ''Mabberley's Plant-Book.'' third edition (2008). Cambridge University ...
'' (family Euphorbiaceae) where the stamens form a ring around the gynoecium, with a single locule.


Pollen production

A typical anther contains four microsporangia. The ''microsporangia'' form sacs or pockets (''locules'') in the anther (anther sacs or pollen sacs). The two separate locules on each side of an anther may fuse into a single locule. Each microsporangium is lined with a nutritive tissue layer called the ''tapetum'' and initially contains diploid pollen mother cells. These undergo meiosis to form
haploid Ploidy () is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomal genes. Sets of chromosomes refer to the number of maternal and paternal chromosome copies, respective ...
spores. The spores may remain attached to each other in a tetrad or separate after meiosis. Each microspore then divides mitotically to form an immature microgametophyte called a pollen grain. The pollen is eventually released when the anther forms openings ( dehisces). These may consist of longitudinal slits, pores, as in the heath family ( Ericaceae), or by valves, as in the
barberry ''Berberis'' (), commonly known as barberry, is a large genus of deciduous and evergreen shrubs from tall, found throughout temperate and subtropical regions of the world (apart from Australia). Species diversity is greatest in South America an ...
family ( Berberidaceae). In some plants, notably members of
Orchidaceae Orchids are plants that belong to the family Orchidaceae (), a diverse and widespread group of flowering plants with blooms that are often colourful and fragrant. Along with the Asteraceae, they are one of the two largest families of flowerin ...
and Asclepiadoideae, the pollen remains in masses called pollinia, which are adapted to attach to particular pollinating agents such as birds or insects. More commonly, mature pollen grains separate and are dispensed by wind or water, pollinating insects, birds or other pollination vectors. Pollen of angiosperms must be transported to the stigma, the receptive surface of the ''
carpel Gynoecium (; ) is most commonly used as a collective term for the parts of a flower that produce ovules and ultimately develop into the fruit and seeds. The gynoecium is the innermost whorl of a flower; it consists of (one or more) '' pistils' ...
'', of a compatible flower, for successful
pollination Pollination is the transfer of pollen from an Stamen, anther of a plant to the stigma (botany), stigma of a plant, later enabling fertilisation and the production of seeds, most often by an animal or by Anemophily, wind. Pollinating agents can ...
to occur. After arriving, the pollen grain (an immature microgametophyte) typically completes its development. It may grow a pollen tube and undergoing mitosis to produce two sperm nuclei.


Sexual reproduction in plants

In the typical flower (that is, in the majority of flowering plant species) each flower has both
carpels Gynoecium (; ) is most commonly used as a collective term for the parts of a flower that produce ovules and ultimately develop into the fruit and seeds. The gynoecium is the innermost whorl of a flower; it consists of (one or more) '' pistils' ...
and stamens. In some species, however, the flowers are unisexual with only carpels or stamens. (
monoecious Monoecy (; adj. monoecious ) is a sexual system in seed plants where separate male and female cones or flowers are present on the same plant. It is a monomorphic sexual system alongside gynomonoecy, andromonoecy and trimonoecy. Monoecy is ...
= both types of flowers found on the same plant;
dioecious Dioecy (; ; adj. dioecious , ) is a characteristic of a species, meaning that it has distinct individual organisms (unisexual) that produce male or female gametes, either directly (in animals) or indirectly (in seed plants). Dioecious reproducti ...
= the two types of flower found only on different plants). A flower with only stamens is called androecious. A flower with only carpels is called gynoecious. A flower having only functional stamens and lacking functional carpels is called a staminate flower, or (inaccurately) male.Encyclopædia Britannica.com
/ref> A plant with only functional
carpel Gynoecium (; ) is most commonly used as a collective term for the parts of a flower that produce ovules and ultimately develop into the fruit and seeds. The gynoecium is the innermost whorl of a flower; it consists of (one or more) '' pistils' ...
s is called pistillate, or (inaccurately) female. An abortive or rudimentary stamen is called a staminodium or
staminode In botany, a staminode is an often rudimentary, sterile or abortive stamen, which means that it does not produce pollen.Jackson, Benjamin, Daydon; ''A Glossary of Botanic Terms with their Derivation and Accent''; Published by Gerald Duckworth & C ...
, such as in ''
Scrophularia nodosa ''Scrophularia nodosa'' (also called figwort, woodland figwort, and common figwort) is a perennial herbaceous plant found in temperate regions of the Northern hemisphere except western North America. It grows in moist and cultivated waste ground. ...
''. The
carpels Gynoecium (; ) is most commonly used as a collective term for the parts of a flower that produce ovules and ultimately develop into the fruit and seeds. The gynoecium is the innermost whorl of a flower; it consists of (one or more) '' pistils' ...
and stamens of
orchid Orchids are plants that belong to the family Orchidaceae (), a diverse and widespread group of flowering plants with blooms that are often colourful and fragrant. Along with the Asteraceae, they are one of the two largest families of floweri ...
s are fused into a
column A column or pillar in architecture and structural engineering is a structural element that transmits, through compression (physical), compression, the weight of the structure above to other structural elements below. In other words, a column i ...
. The top part of the column is formed by the anther, which is covered by an anther cap.


Terminology

;Stamen Stamens can also be adnate (fused or joined from more than one whorl): * epipetalous: adnate to the
corolla Corolla may refer to: *Corolla (botany), the petals of a flower, considered as a unit *Toyota Corolla, an automobile model name *Corolla (headgear) A ''corolla'' is an ancient headdress in the form of a small circlet or crown.tepal A tepal is one of the outer parts of a flower (collectively the perianth). The term is used when these parts cannot easily be classified as either sepals or petals. This may be because the parts of the perianth are undifferentiated (i.e. of very ...
s (as in many
Liliaceae The lily family, Liliaceae, consists of about 15 genera and 610 species of flowering plants within the order Liliales. They are monocotyledonous, perennial, herbaceous, often bulbous geophytes. Plants in this family have evolved with a fair ...
) They can have different lengths from each other: * didymous: two equal pairs * didynamous: occurring in two pairs, a long pair and a shorter pair * tetradynamous: occurring as a set of six stamens with four long and two shorter ones or respective to the rest of the flower (
perianth The perianth (perigonium, perigon or perigone in monocots) is the non-reproductive part of the flower, and structure that forms an envelope surrounding the sexual organs, consisting of the calyx (sepals) and the corolla ( petals) or tepals when ...
): * exserted: extending beyond the corolla * included: not extending beyond the corolla They may be arranged in one of two different patterns: * spiral; or * whorled: one or more discrete whorls (series) They may be arranged, with respect to the petals: * diplostemonous: in two whorls, the outer alternating with the petals, while the inner is opposite the petals. * haplostemenous: having a single series of stamens, equal in number to the proper number of petals and alternating with them * obdiplostemonous: in two whorls, with twice the number of stamens as petals, the outer opposite the petals, inner opposite the sepals, e.g. Simaroubaceae (''see
diagram A diagram is a symbolic representation of information using visualization techniques. Diagrams have been used since prehistoric times on walls of caves, but became more prevalent during the Enlightenment. Sometimes, the technique uses a three ...
'') ;Connective Where the connective is very small, or imperceptible, the anther lobes are close together, and the connective is referred to as discrete, e.g. '' Euphorbia'' pp., '' Adhatoda zeylanica''. Where the connective separates the anther lobes, it is called divaricate, e.g. ''
Tilia ''Tilia'' is a genus of about 30 species of trees or bushes, native throughout most of the temperate Northern Hemisphere. The tree is known as linden for the European species, and basswood for North American species. In Britain and Ireland they ...
'', '' Justicia gendarussa''. The connective may also be a long and stalk-like, crosswise on the filament, this is a distractile connective, e.g. ''
Salvia ''Salvia'' () is the largest genus of plants in the sage family Lamiaceae, with nearly 1000 species of shrubs, herbaceous perennials, and annuals. Within the Lamiaceae, ''Salvia'' is part of the tribe Mentheae within the subfamily Nepetoide ...
''. The connective may also bear appendages, and is called appendiculate, e.g. ''
Nerium odorum ''Nerium oleander'' ( ), most commonly known as oleander or nerium, is a shrub or small tree cultivated worldwide in temperate and subtropical areas as an ornamental and landscaping plant. It is the only species currently classified in the ge ...
'' and some other species of
Apocynaceae Apocynaceae (from '' Apocynum'', Greek for "dog-away") is a family of flowering plants that includes trees, shrubs, herbs, stem succulents, and vines, commonly known as the dogbane family, because some taxa were used as dog poison Members ...
. In ''Nerium'', the appendages are united as a staminal corona. ;Filament A column formed from the fusion of multiple filaments is known as an androphore. Stamens can be connate (fused or joined in the same whorl) as follows: * extrorse: anther dehiscence directed away from the centre of the flower. Cf. introrse, directed inwards, and latrorse towards the side. * monadelphous: fused into a single, compound structure * declinate: curving downwards, then up at the tip (also – declinate-descending) * diadelphous: joined partially into two androecial structures * pentadelphous: joined partially into five androecial structures * synandrous: only the anthers are connate (such as in the
Asteraceae The family Asteraceae, alternatively Compositae, consists of over 32,000 known species of flowering plants in over 1,900 genera within the order Asterales. Commonly referred to as the aster, daisy, composite, or sunflower family, Compositae ...
). The fused stamens are referred to as a synandrium. ;Anther Anther shapes are variously described by terms such as linear, rounded, sagittate, sinuous, or reniform. The anther can be attached to the filament's connective in two ways: * basifixed: attached at its base to the filament ** pseudobasifixed: a somewhat misnomer configuration where connective tissue extends in a tube around the filament tip * dorsifixed: attached at its center to the filament, usually versatile (able to move)


Gallery


References


Bibliography

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External links

{{Authority control Plant anatomy Plant morphology Plant sexuality Plant reproductive system Pollination