The stigma () is the receptive tip of a

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'' ...

, or of several fused carpels, in 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) ''pistils'' ...

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 mechani ...

Description

The stigma, together with the style and

ovary The ovary is an organ in the female reproductive system that produces an ovum. When released, this travels down the fallopian tube into the uterus, where it may become fertilized by a sperm. There is an ovary () found on each side of the body. ...

(typically called the stigma-style-ovary system) comprises the

pistil 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'' ...

, which is part of the

or female reproductive organ of a plant. The stigma itself forms the distal portion of the style, or stylodia, and is composed of , the cells of which are receptive to pollen. These may be restricted to the apex of the style or, especially in wind pollinated species, cover a wide surface. The stigma receives

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 gametophyt ...

and it is on the stigma that the pollen grain germinates. Often sticky, the stigma is adapted in various ways to catch and trap pollen with various hairs, flaps, or sculpturings. The pollen may be captured from the air (wind-borne pollen,

anemophily Anemophily or wind pollination is a form of pollination whereby pollen is distributed by wind. Almost all gymnosperms are anemophilous, as are many plants in the order Poales, including grasses, sedges, and rushes. Other common anemophilous plan ...

), from visiting insects or other animals (

biotic pollination Pollination is the transfer of pollen from an anther of a plant to the stigma of a plant, later enabling fertilisation and the production of seeds, most often by an animal or by wind. Pollinating agents can be animals such as insects, birds, a ...

), or in rare cases from surrounding water (

hydrophily Hydrophily is a fairly uncommon form of pollination whereby pollen is distributed by the flow of waters, particularly in rivers and streams. Hydrophilous species fall into two categories: (i) Those that distribute their pollen to the surface o ...

). Stigma can vary from long and slender to globe shaped to feathery. Pollen is typically highly desiccated when it leaves an anther. Stigma have been shown to assist in the rehydration of pollen and in promoting germination of the pollen tube. Stigma also ensure proper adhesion of the correct species of pollen. Stigma can play an active role in pollen discrimination and some self-incompatibility reactions, that reject pollen from the same or genetically similar plants, involve interaction between the stigma and the surface of the pollen grain.

Shape

The stigma is often split into lobes, e.g. trifid (three lobed), and may resemble the head of a pin (capitate), or come to a point (punctiform). The shape of the stigma may vary considerably: Cornsilk 7091

Style

Structure

The style is a narrow upward extension of the ovary, connecting it to the stigmatic papillae. Occasionally it may be absent, in which case the stigma is described as

sessile Sessility, or sessile, may refer to: * Sessility (motility), organisms which are not able to move about * Sessility (botany), flowers or leaves that grow directly from the stem or peduncle of a plant * Sessility (medicine), tumors and polyps that ...

. Styles are generally tube-like—either long or short. The style can be open (containing few or no cells in the central portion) with a central canal which may be filled with

mucilage Mucilage is a thick, gluey substance produced by nearly all plants and some microorganisms. These microorganisms include protists which use it for their locomotion. The direction of their movement is always opposite to that of the secretion of m ...

. Alternatively the style may be closed (densely packed with cells throughout). Most

syncarpous 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'' ...

monocots Monocotyledons (), commonly referred to as monocots, (Lilianae ''sensu'' Chase & Reveal) are grass and grass-like flowering plants (angiosperms), the seeds of which typically contain only one embryonic leaf, or cotyledon. They constitute one of t ...

and some

eudicots The eudicots, Eudicotidae, or eudicotyledons are a clade of flowering plants mainly characterized by having two seed leaves upon germination. The term derives from Dicotyledons. Traditionally they were called tricolpates or non-magnoliid dico ...

have open styles, while many syncarpous eudicots and grasses have closed (solid) styles containing specialised secretory transmitting tissue, linking the stigma to the centre of the ovary. This forms a nutrient rich tract for pollen tube growth. Where there are more than one carpel to the pistil, each may have a separate style-like stylodium, or share a common style. In Irises and others in the family

Iridaceae Iridaceae is a family of plants in order Asparagales, taking its name from the irises, meaning rainbow, referring to its many colours. There are 66 accepted genera with a total of c. 2244 species worldwide (Christenhusz & Byng 2016). It include ...

, the style divides into three petal-like (petaloid) ''style branches'' (sometimes also referred to as 'stylodia'), almost to the base of the style and is called a . These are flaps of tissue, running from the perianth tube above the sepal. The stigma is a rim or edge on the underside of the branch, near the end lobes. Style branches also appear on ''

Dietes ''Dietes'' is a genus of rhizomatous plants of the family Iridaceae, first described as a genus in 1866. Common names include wood iris, fortnight lily, African iris, Japanese iris and butterfly iris, each of which may be used differently in diff ...

'', ''

Pardanthopsis ''Iris'' is a flowering plant genus of 310 accepted species with showy flowers. As well as being the scientific name, ''iris'' is also widely used as a common name for all ''Iris'' species, as well as some belonging to other closely related gen ...

'' and most species of ''

Moraea ''Moraea'', the Cape tulips, is a genus of plants in the family Iridaceae, first described as a genus in 1758. The group is widespread across Africa, the Mediterranean, and central and southwestern Asia. The genus name is a tribute to the English ...

''.Klaus Kubitzki (Editor) In ''

Crocus ''Crocus'' (; plural: crocuses or croci) is a genus of seasonal flowering plants in the family Iridaceae (iris family) comprising about 100 species of perennials growing from corms. They are low growing plants, whose flower stems remain undergro ...

'' there are three divided style branches, creating a tube.Michael Hickey, Clive King ''

Hesperantha ''Hesperantha'' is a genus of cormous flowering plants in the family Iridaceae. The genus name is derived from the Greek words ''hesperos'', meaning "evening", and ''anthos'', meaning "flower". There are approximately 79 species, mostly native t ...

'' has a spreading style branch. Alternatively the style may be lobed rather than branched. ''

Gladiolus ''Gladiolus'' (from Latin, the diminutive of ''gladius'', a sword) is a genus of perennial cormous flowering plants in the iris family (Iridaceae). It is sometimes called the 'sword lily', but is usually called by its generic name (plural ''g ...

'' has a bi-lobed style branch (bilobate). ''

Freesia ''Freesia'' is a genus of herbaceous perennial flowering plants in the family Iridaceae, first described as a genus in 1866 by Christian Friedrich Ecklon (1886) and named after the German botanist and medical practitioner, Friedrich Freese (1795 ...

'', ''

Lapeirousia ''Lapeirousia'' is a genus in the plant family Iridaceae. It is endemic to sub-Saharan Africa, about a third of the species occurring in fynbos. Origin of the generic name The genus ''Lapeirousia'' was described by Pierre André Pourret in Mé ...

'', ''

Romulea ''Romulea'' is a genus of flowering plants in the family Iridaceae, first described as a genus in 1772. It is distributed in Europe, the Mediterranean, the Arabian Peninsula, and Africa.Savannosiphon ''Savannosiphon'' is a genus of flowering plants in the family Iridaceae, first described as a new species in 1980. It contains only one known species, ''Savannosiphon euryphylla'', native to tropical Africa (Zaire, Tanzania, Malawi, Mozambique, ...

'' and '' Watsonia'' have bifurcated (two branched) and recurved style branches.

Attachment to the ovary

May be terminal (apical), subapical, lateral, gynobasic, or . Terminal (apical) style position refers to attachment at the apex of the ovary and is the most common pattern. In the subapical pattern the style arises to the side slightly below the apex. a lateral style arises from the side of the ovary and is found in

Rosaceae Rosaceae (), the rose family, is a medium-sized family of flowering plants that includes 4,828 known species in 91 genera. The name is derived from the type genus ''Rosa''. Among the most species-rich genera are ''Alchemilla'' (270), ''Sorbus ...

. The gynobasic style arises from the base of the ovary, or between the ovary lobes and is characteristic of

Boraginaceae Boraginaceae, the borage or forget-me-not family, includes about 2,000 species of shrubs, trees and herbs in 146, to 156 genera with a worldwide distribution. The APG IV system from 2016 classifies the Boraginaceae as single family of the order ...

. styles characterise ''

Allium ''Allium'' is a genus of monocotyledonous flowering plants that includes hundreds of species, including the cultivated onion, garlic, scallion, shallot, leek, and chives. The generic name ''Allium'' is the Latin word for garlic,Gledhill, Davi ...

''.

Pollination

Pollen tubes grow the length of the style to reach the

ovule In seed plants, the ovule is the structure that gives rise to and contains the female reproductive cells. It consists of three parts: the ''integument'', forming its outer layer, the ''nucellus'' (or remnant of the megasporangium), and the fe ...

s, and in some cases self-incompatibility reactions in the style prevent full growth of the pollen tubes. In some species, including ''

Gasteria ''Gasteria'' is a genus of succulent plants, native to South Africa (and the far south-west corner of Namibia). Naming The genus is named for its stomach-shaped flowers (''"gaster"'' is Latin for "stomach") that result from the swollen base on t ...

'' at least, the pollen tube is directed to the

micropyle Micropyle may refer to: * Micropyle (botany) In seed plants, the ovule is the structure that gives rise to and contains the female reproductive cells. It consists of three parts: the ''integument'', forming its outer layer, the ''nucellus'' (o ...

of the ovule by the style.Christophe Clement, Ettore Pacini, Jean-Claude Audran (Editors)

References

Citations

Sources

* * * * * *

External links

Stigma shape and size - English labels

Terminal versus gynobasic style
Images
Gynobasic
Diagram {{botany Plant reproductive system Plant morphology Plant sexuality

Description

Shape

Style

Structure

Attachment to the ovary

Pollination

See also

References

Citations

Sources

External links