Chasmogamy, is a plant reproductive mechanism in which

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 ...

occurs in chasmogamous

flowers 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 ...

. Chasmogamous flowers are commonly showy with open petals encircling exposed reproductive parts. Chasmogamous stems from Greek for "open marriage", named after the open arrangement of floral structures. Once chasmogamous flowers have reached maturity, they unfurl and their

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 filame ...

s and/or

style Style is a manner of doing or presenting things and may refer to: * Architectural style, the features that make a building or structure historically identifiable * Design, the process of creating something * Fashion, a prevailing mode of clothing ...

are made available for pollination. Although some plant species possess self-fertilizing chasmogamous flowers, most chasmogamous flowers are

cross-pollinated 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 ...

by biotic (e.g. insects) or

abiotic In biology and ecology, abiotic components or abiotic factors are non-living chemical and physical parts of the environment that affect living organisms and the functioning of ecosystems. Abiotic factors and the phenomena associated with them under ...

(e.g. wind) agents. Chasmogamous flowers that are cross-pollinated have the advantage of sexual reproduction between two different parents, resulting in

sexual recombination Genetic recombination (also known as genetic reshuffling) is the exchange of genetic material between different organisms which leads to production of offspring with combinations of traits that differ from those found in either parent. In eukaryo ...

and genetically distinct seeds. These distinct seeds increase genetic diversity of the plant population and reduce

inbreeding depression Inbreeding depression is the reduced biological fitness which has the potential to result from inbreeding (the breeding of related individuals). Biological fitness refers to an organism's ability to survive and perpetuate its genetic material. In ...

and deleterious alleles. Seeds produced by chasmogamous flowers that are cross-pollinated, may also exhibit hybrid vigor (

heterosis Heterosis, hybrid vigor, or outbreeding enhancement is the improved or increased function of any biological quality in a hybrid offspring. An offspring is heterotic if its traits are enhanced as a result of mixing the genetic contributions of ...

) and increased fitness. To promote cross-pollination, chasmogamous flowers often have strikingly colored petals and nectar guides/nectaries to attract and reward pollinators. However, these attractive floral organs can be disadvantageous as they are energetically costly to produce and require a surplus of resources. Pollination of chasmogamous flowers is also dependent upon the availability of pollinating agents. Thus, chasmogamous flowers generally develop when resources like light, water, nutrients, and pollinators are high. In contrast to chasmogamous flowers, are minute, bud-like

cleistogamous Cleistogamy is a type of automatic self-pollination of certain plants that can propagate by using non-opening, self-pollinating flowers. Especially well known in peanuts, peas, and pansies, this behavior is most widespread in the grass family. How ...

("closed marriage") flowers, and pollination of cleistogamous flowers is

cleistogamy Cleistogamy is a type of automatic self-pollination of certain plants that can propagate by using non-opening, self-pollinating flowers. Especially well known in peanuts, peas, and pansies, this behavior is most widespread in the grass family. How ...

. Unlike chasmogamous flowers, cleistogamous flowers remain mechanically sealed throughout the entirety of their development and reproduction. The closed morphology of cleistogamous flowers hinders them from exposing their reproductive organs and forces

self-pollination Self-pollination is a form of pollination in which pollen from the same plant arrives at the Stigma (botany), stigma of a flower (in flowering plants) or at the ovule (in gymnosperms). There are two types of self-pollination: in autogamy, pollen i ...

. Without the need for pollinating agents, cleistogamous flowers lack nectar and elaborate petals, making them much less costly to produce than chasmogamous flowers and developmentally favored in suboptimal conditions. In addition to chasmogamy and cleistogamy, many plant species possess a mixed breeding system that utilizes both chasmogamous and cleistogamous flowers. This breeding system has been referred to under multiple names including true cleistogamy, dimorphic cleistogamy, and the chasmogamous/cleistogamous mixed breeding system. In this mixed breeding system, species produce both chasmogamous and cleistogamous flowers on the same plant. Chasmogamous and cleistogamous flowers may exhibit spatial separation and develop simultaneously at different morphological locations, or the two flowers may be temporally separated and develop at different times during the flowering season. Rarely, the two flowers have also been documented as being both spatially and temporally separated. The presence of both flower types allows mixed breeding system species to cross-pollinate and self-fertilize. This leads to increases in genetic diversity and assures reproductive success in variable environmental and pollinator conditions.{{Cite journal, title = Variation strategies of plants in heterogeneous environments., last = Lloyd, first = D. G., date = 1984, journal = Biological Journal of the Linnean Society, doi = 10.1111/j.1095-8312.1984.tb01600.x, volume = 21, issue=4 , pages = 357–385

References

Plant reproduction Pollination

See also

References