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Gynoecium (; ) is most commonly used as a collective term for the parts 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 mechanism ...
that produce
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 f ...
s and ultimately develop into the
fruit In botany, a fruit is the seed-bearing structure in flowering plants that is formed from the ovary after flowering. Fruits are the means by which flowering plants (also known as angiosperms) disseminate their seeds. Edible fruits in partic ...
and
seed A seed is an embryonic plant enclosed in a protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, including the gymnosperm and angiosper ...
s. The gynoecium is the innermost
whorl A whorl ( or ) is an individual circle, oval, volution or equivalent in a whorled pattern, which consists of a spiral or multiple concentric objects (including circles, ovals and arcs). Whorls in nature File:Photograph and axial plane flo ...
of a flower; it consists of (one or more) '' pistils'' and is typically surrounded by 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 organs, the
stamen The stamen (plural ''stamina'' or ''stamens'') is the pollen-producing reproductive organ of a flower. Collectively the stamens form the androecium., p. 10 Morphology and terminology A stamen typically consists of a stalk called the filam ...
s, collectively called the
androecium The stamen ( plural ''stamina'' or ''stamens'') is the pollen-producing reproductive organ of a flower. Collectively the stamens form the androecium., p. 10 Morphology and terminology A stamen typically consists of a stalk called the fila ...
. The gynoecium is often referred to as the " female" portion of the flower, although rather than directly producing female
gamete A gamete (; , ultimately ) is a haploid cell that fuses with another haploid cell during fertilization in organisms that reproduce sexually. Gametes are an organism's reproductive cells, also referred to as sex cells. In species that produce ...
s (i.e.
egg cell The egg cell, or ovum (plural ova), is the female reproductive cell, or gamete, in most anisogamous organisms (organisms that reproduce sexually with a larger, female gamete and a smaller, male one). The term is used when the female gamete is ...
s), the gynoecium produces megaspores, each of which develops into a female
gametophyte A gametophyte () is one of the two alternation of generations, alternating multicellular organism, multicellular phases in the life cycles of plants and algae. It is a haploid multicellular organism that develops from a haploid spore that has on ...
which then produces egg cells. The term gynoecium is also used by botanists to refer to a cluster of archegonia and any associated modified leaves or stems present on a gametophyte shoot in
moss Mosses are small, non-vascular flowerless plants in the taxonomic division Bryophyta (, ) '' sensu stricto''. Bryophyta ('' sensu lato'', Schimp. 1879) may also refer to the parent group bryophytes, which comprise liverworts, mosses, and ...
es, liverworts, and hornworts. The corresponding terms for the male parts of those plants are clusters of antheridia within the androecium. Flowers that bear a gynoecium but no stamens are called ''pistillate'' or ''carpellate''. Flowers lacking a gynoecium are called staminate. The gynoecium is often referred to as female because it gives rise to female (egg-producing) gametophytes; however, strictly speaking sporophytes do not have a sex, only gametophytes do. Gynoecium development and arrangement is important in systematic research and identification of angiosperms, but can be the most challenging of the floral parts to interpret.


Introduction

Unlike most animals, plants grow new organs after
embryogenesis An embryo is an initial stage of development of a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male sperm ...
, including new roots, leaves, and flowers. In the flowering plants, the gynoecium develops in the central region of the flower as a carpel or in groups of fused carpels.
Recent Advances and Challenges on Big Data Analysis in Neuroimaging
'. Frontiers Media SA; 17 May 2017. . p. 158–.
After fertilization, the gynoecium develops into a fruit that provides protection and nutrition for the developing seeds, and often aids in their dispersal. The gynoecium has several specialized tissues.
Molecular basis of fruit development
'. Frontiers Media SA; 26 March 2014. . p. 27–.
The tissues of the gynoecium develop from genetic and hormonal interactions along three-major axes. These tissue arise from meristems that produce cells that differentiation into the different tissues that produce the parts of the gynoecium including the pistil, carpels, ovary, and ovals; the carpel margin meristem (arising from the carpel primordium) produces 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 f ...
s, ovary septum, and the transmitting track, and plays a role in fusing the apical margins of carpels.
Fruit Ripening: From Present Knowledge to Future Development
'. Frontiers Media SA; 12 August 2019. . p. 155–.


Pistil

The gynoecium may consist of one or more separate pistils. A pistil typically consists of an expanded basal portion called an ovary, an elongated section called a style and an apical structure called a stigma that receives pollen. * The ovary (from Latin ''ovum'', meaning egg) is the enlarged basal portion which contains ''placentas'', ridges of tissue bearing one or more ovules (integumented megasporangia). The placentas and/or ovule(s) may be born on the gynoecial appendages or less frequently on the floral apex. The chamber in which the ovules develop is called a ''
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 ...
'' (or sometimes cell). * The style (from Ancient Greek ''στῦλος'', ''stylos'', meaning a pillar) is a pillar-like stalk through which pollen tubes grow to reach the ovary. Some flowers, such as those of '' Tulipa'', do not have a distinct style, and the stigma sits directly on the ovary. The style is a hollow tube in some plants, such as lilies, or has transmitting tissue through which the pollen tubes grow. * The stigma (from Ancient Greek , ''stigma'', meaning mark or puncture) is usually found at the tip of the style, the portion of the carpel(s) that 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 gametop ...
(male
gametophyte A gametophyte () is one of the two alternation of generations, alternating multicellular organism, multicellular phases in the life cycles of plants and algae. It is a haploid multicellular organism that develops from a haploid spore that has on ...
s). It is commonly sticky or feathery to capture pollen. The word "pistil" comes from
Latin Latin (, or , ) is a classical language belonging to the 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 the power ...
''pistillum'' meaning
pestle Mortar and pestle is a set of two simple tools used from the Stone Age to the present day to prepare ingredients or substances by crushing and grinding them into a fine paste or powder in the kitchen, laboratory, and pharmacy. The ''mortar'' ...
. A sterile pistil in a male flower is referred to as a ''pistillode''.


Carpels

The pistils of a flower are considered to be composed of one or more '' carpels''. A carpel is the female reproductive part of the flower—usually composed of the style, and stigma (sometimes having its individual ovary, and sometimes connecting to a shared basal ovary) —and usually interpreted as modified leaves that bear structures called
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 f ...
s, inside which egg cells ultimately form. A pistil may consist of one carpel (with its ovary, style and stigma); or it may comprise several carpels joined together to form a single ovary, the whole unit called a pistil. The gynoecium may present as one or more uni-carpellate pistils or as one multi-carpellate pistil. (The number of carpels is denoted by terms such as ''tricarpellate'' (three carpels).) Carpels are thought to be phylogenetically derived from ovule-bearing leaves or leaf homologues ( megasporophylls), which evolved to form a closed structure containing the ovules. This structure is typically rolled and fused along the margin. Although many flowers satisfy the above definition of a carpel, there are also flowers that do not have carpels because in these flowers the ovule(s), although enclosed, are borne directly on the shoot apex. Different remedies have been suggested for this problem. An easy remedy that applies to most cases is to redefine the carpel as an appendage that encloses ovule(s) and may or may not bear them.


Types

If a gynoecium has a single carpel, it is called ''monocarpous''. If a gynoecium has multiple, distinct (free, unfused) carpels, it is ''apocarpous''. If a gynoecium has multiple carpels "fused" into a single structure, it is ''syncarpous''. A syncarpous gynoecium can sometimes appear very much like a monocarpous gynoecium. The degree of connation ("fusion") in a syncarpous gynoecium can vary. The carpels may be "fused" only at their bases, but retain separate styles and stigmas. The carpels may be "fused" entirely, except for retaining separate stigmas. Sometimes (e.g.,
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 of the ...
) carpels are fused by their styles or stigmas but possess distinct ovaries. In a syncarpous gynoecium, the "fused" ovaries of the constituent carpels may be referred to collectively as a single compound ovary. It can be a challenge to determine how many carpels fused to form a syncarpous gynoecium. If the styles and stigmas are distinct, they can usually be counted to determine the number of carpels. Within the compound ovary, the carpels may have distinct locules divided by walls called ''septa''. If a syncarpous gynoecium has a single style and stigma and a single locule in the ovary, it may be necessary to examine how the ovules are attached. Each carpel will usually have a distinct line of placentation where the ovules are attached.


Pistil development

Pistils begin as small primordia on a floral apical meristem, forming later than, and closer to the (floral) apex than sepal, petal and stamen primordia. Morphological and molecular studies of pistil ontogeny reveal that carpels are most likely homologous to leaves. A carpel has a similar function to a megasporophyll, but typically includes a stigma, and is fused, with ovules enclosed in the enlarged lower portion, the ovary. In some
basal angiosperm The basal angiosperms are the flowering plants which diverged from the lineage leading to most flowering plants. In particular, the most basal angiosperms were called the ANITA grade, which is made up of ''Amborella'' (a single species of shrub f ...
lineages, Degeneriaceae and Winteraceae, a carpel begins as a shallow cup where the ovules develop with laminar placentation, on the upper surface of the carpel. The carpel eventually forms a folded, leaf-like structure, not fully sealed at its margins. No style exists, but a broad stigmatic crest along the margin allows pollen tubes access along the surface and between hairs at the margins. Two kinds of fusion have been distinguished: postgenital fusion that can be observed during the development of flowers, and congenital fusion that cannot be observed i.e., fusions that occurred during phylogeny. But it is very difficult to distinguish fusion and non-fusion processes in the evolution of flowering plants. Some processes that have been considered congenital (phylogenetic) fusions appear to be non-fusion processes such as, for example, the de novo formation of intercalary growth in a ring zone at or below the base of primordia. Therefore, "it is now increasingly acknowledged that the term 'fusion,' as applied to phylogeny (as in 'congenital fusion') is ill-advised."


Gynoecium position

Basal angiosperm groups tend to have carpels arranged spirally around a conical or dome-shaped
receptacle Receptacle may refer to: Biology * Receptacle (botany), a plant anatomical part * Seminal receptacle, a sperm storage site in some insects Electrical engineering * Automobile auxiliary power outlet, formerly known as ''cigarette lighter recep ...
. In later lineages, carpels tend to be in
whorl A whorl ( or ) is an individual circle, oval, volution or equivalent in a whorled pattern, which consists of a spiral or multiple concentric objects (including circles, ovals and arcs). Whorls in nature File:Photograph and axial plane flo ...
s. The relationship of the other flower parts to the gynoecium can be an important systematic and taxonomic character. In some flowers, the stamens, petals, and sepals are often said to be "fused" into a "floral tube" or ''
hypanthium In angiosperms, a hypanthium or floral cup is a structure where basal portions of the calyx, the corolla, and the stamens form a cup-shaped tube. It is sometimes called a floral tube, a term that is also used for corolla tube and calyx tube. It ...
''. However, as Leins & Erbar (2010) pointed out, "the classical view that the wall of the inferior ovary results from the "congenital" fusion of dorsal carpel flanks and the floral axis does not correspond to the ontogenetic processes that can actually be observed. All that can be seen is an intercalary growth in a broad circular zone that changes the shape of the floral axis (receptacle)." And what happened during evolution is not a phylogenetic fusion but the formation of a unitary intercalary meristem. Evolutionary developmental biology investigates such developmental processes that arise or change during evolution. If the hypanthium is absent, the flower is ''hypogynous'', and the stamens, petals, and sepals are all attached to the receptacle below the gynoecium. Hypogynous flowers are often referred to as having a ''superior ovary''. This is the typical arrangement in most flowers. If the hypanthium is present up to the base of the style(s), the flower is ''epigynous''. In an epigynous flower, the stamens, petals, and sepals are attached to the hypanthium at the top of the ovary or, occasionally, the hypanthium may extend beyond the top of the ovary. Epigynous flowers are often referred to as having an ''inferior ovary''. Plant families with epigynous flowers include orchids, asters, and
evening primroses ''Oenothera'' is a genus of about 145 species of herbaceous flowering plants native to the Americas. It is the type genus of the family Onagraceae. Common names include evening primrose, suncups, and sundrops. They are not closely related to ...
. Between these two extremes are ''perigynous'' flowers, in which a hypanthium is present, but is either free from the gynoecium (in which case it may appear to be a cup or tube surrounding the gynoecium) or connected partly to the gynoecium (with the stamens, petals, and sepals attached to the hypanthium part of the way up the ovary). Perigynous flowers are often referred to as having a ''half-inferior ovary'' (or, sometimes, ''partially inferior'' or ''half-superior''). This arrangement is particularly frequent in the rose family and
saxifrages ''Saxifraga'' is the largest genus in the family Saxifragaceae, containing about 473 species of holarctic perennial plants, known as saxifrages or rockfoils. The Latin word ''saxifraga'' means literally "stone-breaker", from Latin ' ("rock" or " ...
. Occasionally, the gynoecium is born on a stalk, called the gynophore, as in ''Isomeris arborea''. Image:Spathoglottis flwrs reduced.jpg, Flowers and fruit (capsules) of the ground orchid, ''
Spathoglottis ''Spathoglottis'', commonly known as purple orchids or 苞舌兰属 (bao she lan shu) is a genus of about fifty species of orchids in the family Orchidaceae. They are evergreen terrestrial herbs with crowded pseudobulbs, a small number of leaves ...
plicata'', illustrating an inferior ovary. Image:Hegi ovary.png, Illustration showing longitudinal sections through hypogynous (a), perigynous (b), and epigynous (c) flowers


Placentation

Within the ovary, each ovule is born by a placenta or arises as a continuation of the floral apex. The placentas often occur in distinct lines called lines of
placentation Placentation refers to the formation, type and structure, or arrangement of the placenta. The function of placentation is to transfer nutrients, respiratory gases, and water from maternal tissue to a growing embryo, and in some instances to remov ...
. In monocarpous or apocarpous gynoecia, there is typically a single line of placentation in each ovary. In syncarpous gynoecia, the lines of placentation can be regularly spaced along the wall of the ovary (''parietal placentation''), or near the center of the ovary. In the latter case, separate terms are used depending on whether or not the ovary is divided into separate locules. If the ovary is divided, with the ovules born on a line of placentation at the inner angle of each locule, this is ''axile placentation''. An ovary with ''free central placentation'', on the other hand, consists of a single compartment without septae and the ovules are attached to a central column that arises directly from the floral apex (axis). In some cases a single ovule is attached to the bottom or top of the locule (''basal'' or ''apical placentation'', respectively).


The ovule

In flowering plants, the ''ovule'' (from Latin ''ovulum'' meaning small egg) is a complex structure born inside ovaries. The ovule initially consists of a stalked, integumented ''megasporangium'' (also called the ''nucellus''). Typically, one cell in the megasporangium undergoes
meiosis Meiosis (; , since it is a reductional division) is a special type of cell division of germ cells in sexually-reproducing organisms that produces the gametes, such as sperm or egg cells. It involves two rounds of division that ultimately ...
resulting in one to four megaspores. These develop into a megagametophyte (often called the embryo sac) within the ovule. The megagametophyte typically develops a small number of cells, including two special cells, an egg cell and a binucleate central cell, which are the
gamete A gamete (; , ultimately ) is a haploid cell that fuses with another haploid cell during fertilization in organisms that reproduce sexually. Gametes are an organism's reproductive cells, also referred to as sex cells. In species that produce ...
s involved in double fertilization. The central cell, once fertilized by a sperm cell from the pollen becomes the first cell of the endosperm, and the egg cell once fertilized become the
zygote A zygote (, ) is a eukaryotic cell formed by a fertilization event between two gametes. The zygote's genome is a combination of the DNA in each gamete, and contains all of the genetic information of a new individual organism. In multicell ...
that develops into the
embryo An embryo is an initial stage of development of a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male sperm ...
. The gap in the integuments through which the pollen tube enters to deliver sperm to the egg is called the
micropyle Micropyle may refer to: * Micropyle (botany) a minute opening in the integument of an ovule of a seed plant. * Micropyle (zoology) A micropyle is a pore in the membrane covering the ovum, through which a sperm enters. Micropyles are also found in ...
. The stalk attaching the ovule to the placenta is called the funiculus.


Role of the stigma and style

Stigmas can vary from long and slender to globe-shaped to feathery. The stigma is the receptive tip of the carpel(s), which receives pollen at pollination and on which the pollen grain
germinates Germination is the process by which an organism grows from a seed or spore. The term is applied to the sprouting of a seedling from a seed of an flowering plant, angiosperm or gymnosperm, the growth of a sporeling from a spore, such as the spor ...
. The stigma is adapted to catch and trap pollen, either by combining pollen of visiting insects or by various hairs, flaps, or sculpturings. The style and stigma of the flower are involved in most types of self incompatibility reactions. Self-incompatibility, if present, prevents
fertilization Fertilisation or fertilization (see spelling differences), also known as generative fertilisation, syngamy and impregnation, is the fusion of gametes to give rise to a new individual organism or offspring and initiate its development. Pro ...
by pollen from the same plant or from genetically similar plants, and ensures outcrossing. The primitive development of carpels, as seen in such groups of plants as '' Tasmannia'' and '' Degeneria'', lack styles and the stigmatic surface is produced along the carpels margins.Armen Takhtajan.
Flowering Plants
'. Springer Science & Business Media; 6 July 2009. . p. 22–.
Image:Marijuana Pistil.jpg, Stigmas and style of ''Cannabis sativa'' held in a pair of forceps File:Crocus macro crop.jpg, Stigma of a '' Crocus'' flower.


See also

* Chalaza


Notes


References


Bibliography

* * {{Authority control Plant reproductive system Plant morphology Plant sexuality