Hermaphrodite in the context of Sexual selection in flowering plants

Sex is the biological trait that determines whether an anisogamous sexually reproducing organism produces male or female gametes. During sexual reproduction, a male and a female gamete fuse to form a zygote, which develops into an offspring that inherits traits from each parent. By convention, organisms that produce smaller gametes (spermatozoa, sperm) are called male, while organisms that produce larger gametes (ova, often called egg cells) are called female. An organism that produces both types of gamete is a hermaphrodite.

In non-hermaphroditic species, the sex of an individual is determined through one of several biological sex-determination systems. Most mammalian species have the XY sex-determination system, where the male usually carries an X and a Y chromosome (XY), and the female usually carries two X chromosomes (XX). Other chromosomal sex-determination systems in animals include the ZW system in birds, and the XO system in some insects. Various environmental systems include temperature-dependent sex determination in reptiles and crustaceans.

Stipa is a genus of about 140 species of large perennial hermaphroditic grasses collectively known as feather grass, needle grass, and spear grass. They are placed in the subfamily Pooideae and the tribe Stipeae, which also contains many species formerly assigned to Stipa, which have since been reclassified into new genera.

Many species are important forage crops. Several species such as Stipa brachytricha, S. arundinacea, S. splendens, S. gigantea and S. pulchra are used as ornamental plants. One former species, esparto grass (Macrochloa tenacissima), is used for crafts and extensively in paper making.

In biology, mating is the pairing of either opposite-sex or hermaphroditic organisms for the purposes of sexual reproduction. Fertilization is the fusion of two gametes. Copulation is the union of the sex organs of two sexually reproducing animals for insemination and subsequent internal fertilization. Mating may also lead to external fertilization, as seen in amphibians, bony fishes and plants. For most species, mating is between two individuals of opposite sexes. However, for some hermaphroditic species, copulation is not required because the parent organism is capable of self-fertilization (autogamy); for example, banana slugs.

The term mating is also applied to related processes in bacteria, archaea and viruses. Mating in these cases involves the pairing of individuals, accompanied by the pairing of their homologous chromosomes and then exchange of genomic information leading to formation of recombinant progeny (see mating systems).

Caenorhabditis elegans (/ˌsiːnoʊræbˈdaɪtəs ˈɛləɡæns/) is a free-living transparent nematode about 1 mm in length that lives in temperate soil environments. It is the type species of its genus. The name is a blend of the Greek caeno- (recent), rhabditis (rod-like) and Latin elegans (elegant). In 1900, Maupas initially named it Rhabditides elegans. Osche placed it in the subgenus Caenorhabditis in 1952, and in 1955, Dougherty raised Caenorhabditis to the status of genus.

C. elegans is an unsegmented pseudocoelomate and lacks respiratory or circulatory systems. Most of these nematodes are hermaphrodites and a few are males. Males have specialised tails for mating that include spicules.

Vitis vinifera, the common grape vine, is a species of flowering plant, native to the Mediterranean region, Central Europe, and southwestern Asia, from Morocco and Portugal north to southern Germany and east to northern Iran. As of 2012, there were between 5,000 and 10,000 varieties of Vitis vinifera grapes though only a few are of commercial significance for wine and table grape production.

The wild grape is often classified as Vitis vinifera sylvestris (in some classifications considered Vitis sylvestris), with Vitis vinifera vinifera restricted to cultivated forms. Domesticated vines have hermaphrodite flowers, but sylvestris is dioecious (male and female flowers on separate plants) and pollination is required for fruit to develop.

Leeches are segmented parasitic or predatory worms that comprise the subclass Hirudinea within the phylum Annelida. They are closely related to the oligochaetes, which include the earthworm, and like them have soft, muscular segmented bodies that can lengthen and contract. Both groups are hermaphrodites and have a clitellum, but leeches typically differ from the oligochaetes in having suckers at both ends and ring markings that do not correspond with their internal segmentation. The body is muscular and relatively solid; the coelom, the spacious body cavity found in other annelids, is reduced to small channels.

The majority of leeches live in freshwater habitats, while some species can be found in terrestrial or marine environments. The best-known species, such as the medicinal leech, Hirudo medicinalis, are hematophagous, attaching themselves to a host with a sucker and feeding on blood, having first secreted the peptide hirudin to prevent the blood from clotting. The jaws used to pierce the skin are replaced in other species by a proboscis which is pushed into the skin. A minority of leech species are predatory, mostly preying on small invertebrates.

In many animals, a penis (/ˈpiːnɪs/; pl.: penises or penes) is the main male sexual organ used to inseminate females (or hermaphrodites) during copulation. Such organs occur in both vertebrates and invertebrates, but males do not bear a penis in every animal species. Furthermore, penises are not necessarily homologous.

The term penis applies to many intromittent organs, but not to all. As an example, the intromittent organ of most Cephalopoda is the hectocotylus, a specialized arm, and male spiders use their pedipalps. Even within the Vertebrata, there are morphological variants with specific terminology, such as hemipenes.

A sex-determination system is a biological system that determines the development of the organism's sex. Most organisms that create their offspring using sexual reproduction have two common sexes, males and females, and in other species there are hermaphrodites, organisms that can function reproductively as either female or male, or both.

There are also some species in which only one sex is present, temporarily or permanently. This can be due to parthenogenesis, the act of a female reproducing without fertilization, mostly seen in plant species. In some plants or algae the gametophyte stage may reproduce itself, thus producing more individuals of the same sex as the parent.

Allogamy or cross-fertilization is thefertilization of an ovum from one individual with the spermatozoa of another. By contrast, autogamy is the term used for self-fertilization. In humans, the fertilization event is an instance of allogamy. Self-fertilization occurs in hermaphroditic organisms where the two gametes fused in fertilization come from the same individual. This is common in plants (see Sexual reproduction in plants) and certain protozoans.

In plants, allogamy is used specifically to mean the use of pollen from one plant to fertilize the flower of another plant and usually synonymous with the term "cross-fertilization" or "cross-pollination" (outcrossing). The latter term can be used more specifically to mean pollen exchange between different plant strains or even different plant species (where the term cross-hybridization can be used) rather than simply between different individuals.

In chemistry, a zwitterion (/ˈtsvɪtərˌaɪɔːn/ TSVIT-ər-EYE-awn; from German Zwitter [ˈtsvɪtɐ] 'hermaphrodite'), also called an inner salt or dipolar ion, is a molecule that contains an equal number of positively and negatively charged functional groups.(1,2-dipolar compounds, such as ylides, are sometimes excluded from the definition.)

Some zwitterions, such as amino acid zwitterions, are in chemical equilibrium with an uncharged "parent" molecule. Betaines are zwitterions that cannot isomerize to an all-neutral form, such as when the positive charge is located on a quaternary ammonium group. Similarly, a molecule containing a phosphonium group and a carboxylate group cannot isomerize.

Zelkova (from the Georgian dzelkva, 'stone pillar') is a genus of six species of deciduous trees in the elm family Ulmaceae, native to southern Europe, and southwest and eastern Asia. They vary in size from shrubs (Z. sicula) to large trees up to 35 m (115 ft) tall (Z. carpinifolia). The bark is smooth, dark brown. Unlike elms, the branchlets are never corky or winged. The leaves are alternate, with serrated margins, and (unlike the related elms) a symmetrical base to the leaf blade. The leaves are in two distinct rows; they have pinnate venation and each vein extends to the leaf margin, where it terminates in a tooth. There are two stipules at each node, though these are caducous (shed early), leaving a pair of scars at the leaf base. Zelkova is polygamous. Staminate flowers are clustered in the lower leaf axils of young branchlets; the perianth is campanulate, with four to six (to seven) lobes, and the stamens are short. Pistillate and hermaphrodite flowers are solitary, or rarely in clusters of two to four, in the upper leaf axils of young branchlets. The fruit is a dry, nut-like drupe with a dorsal keel, produced singly in the leaf axils. The perianth and stigma are persistent.

Trioecy /traɪˈiːsi/, also spelled triecy, is a sexual system characterized by the coexistence of males, females, and hermaphrodites. It has been found in both plants and animals. Like androdioecy and gynodioecy, trioecy is a mixed mating systems.

Gynomonoecy is defined as the presence of both female and hermaphrodite flowers on the same individual of a plant species. It is prevalent in Asteraceae but is poorly understood.

It is a monomorphic sexual system comparable with monoecy, andromonoecy and trimonoecy.

Andromonoecy is a breeding system of plant species in which male and hermaphrodite flowers are on the same plant. It is a monomorphic sexual system comparable with monoecy, gynomonoecy and trimonoecy. Andromonoecy is frequent among genera with zygomorphic flowers, however it is overall rare and occurs in less than 2% of plant species. Nonetheless the breeding system has gained interest among biologists in the study of sex expression.

Trimonoecy, also called polygamomonoecy, is when male, female, and hermaphrodite flowers are on the same plant. Trimonoecy is rare.

It is a monomorphic sexual system along with monoecy, gynomonoecy, and andromonoecy. It is hypothesized that trimonoecy originated from gynomonoecy.

Simultaneous hermaphroditism is one of the two types of hermaphroditism, the other type being sequential hermaphroditism. In this form of hermaphroditism an individual has sex organs of both sexes and can produce both gamete types even in the same breeding season.

The distinction between simultaneous hermaphroditism and sequential hermaphroditism is not always clear. But unlike sequential hermaphrodites, simultaneous hermaphrodites are both male and female at sexual maturity. Also sex determination does not apply to simultaneous hermaphrodites (except in species with mix mating systems). In simultaneous hermaphrodites, self-fertilization is possible in some species, where in others it is absent.