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Tristyly
Tristyly is a rare floral polymorphism that consists of three floral morphs that differ in regard to the length of the stamens and style within the flower. This type of floral mechanism is thought to encourage outcross pollen transfer and is usually associated with heteromorphic self-incompatibility to reduce inbreeding. It is an example of heterostyly and reciprocal herkogamy, like distyly, which is the more common form of heterostyly. Darwin first described tristylous species in 1877 in terms of the incompatibility of these three morphs. Description The three floral morphs of tristylous plants are based on the positioning of the male and female reproductive structures, as either long-, mid-, or short-styled morphs. Often this is shortened to L, M and S morphs. There are two different lengths of stamens in each flower morph that oppose the length of the style. For example, in the short-styled morph, the two sets of stamen are arranged in the mid and long position in order to pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heterostyly
Heterostyly is a unique form of polymorphism and herkogamy in flowers. In a heterostylous species, two or three morphological types of flowers, termed "morphs", exist in the population. On each individual plant, all flowers share the same morph. The flower morphs differ in the lengths of the pistil and stamens, and these traits are not continuous. The morph phenotype is genetically linked to genes responsible for a unique system of self-incompatibility, termed heteromorphic self-incompatibility, that is, the pollen from a flower on one morph cannot fertilize another flower of the same morph. Heterostylous plants having two flower morphs are termed " distylous". In one morph (termed "pin", "longistylous", or "long-styled" flower) the stamens are short and the pistils are long; in the second morph (termed "thrum", "brevistylous", or "short-styled" flower) the stamens are long and the pistils are short; the length of the pistil in one morph equals the length of the stamens in th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pontederiaceae
Pontederiaceae is a Family (biology), family of flowering plants. The APG IV system of 2016 (unchanged from the APG III system of 2009, the APG II system of 2003 and the APG system of 1998) places the family in the order Commelinales, in the commelinid clade, in the Monocotyledon, monocots. It is a small family of heterostyly, heterostylous aquatic plants, occurring in Tropics, tropical and Subtropics, subtropical waters. Charles Darwin was interested in the specialized form of heterostyly found in the family, known as tristyly. Not all of the species are heterostylous. The family contains two genera with around 40 known species. It is best known for the water hyacinth (''Eichhornia crassipes, Pontederia crassipes''), which is an invasive species in many waterways. The highly modified ''Hydrothrix gardneri, Heteranthera gardneri'' is a submerged aquatic with a two-flowered pseudanthium. Taxonomy The two genera within this family are: *''Heteranthera'' Ruiz y Pavón, Ruiz & Pav ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Style (flower)
In botany, the style of an angiosperm flower is an organ of variable length that connects the ovary to the stigma. The style does not contain ovules; these are limited to the region of the gynoecium (female organs of the flower) called the "ovary". Structure The style is a narrow extension of the ovary, usually pointing upwards, connecting the ovary to the stigmatic papillae. It may be absent in some plants; in this case, it is referred to as a sessile stigma. Styles generally resemble more or less long tubes. The style can be open (with few cells occupying the central part, or even none), featuring a central canal that may be filled with mucilage. Alternatively, the style can be closed (completely filled with cells). Most plants with syncarpous pistils ( monocotyledons and some eudicotys) have open styles, whereas many eudicots and grasses have closed (solid) styles containing specialized secretory tissues, which connect the stigma to the center of the ovary. These tissue ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Herkogamy
Herkogamy (or hercogamy) is the spatial separation of the anthers and stigma in hermaphroditic angiosperms. It is a common strategy for reducing self-fertilization. Common forms *Approach herkogamy - (called "pin flowers") is displayed when the stigma is displayed above the level of the anthers. This arrangement of sex organs causes floral visitors to first contact the stigma, before removing pollen from the anthers. This form of herkogamy is considered to be common, and is associated with a large, diverse fauna of floral visitors/pollinators. *Reverse herkogamy - (called "thrum flowers") is displayed when the stigma is recessed below the level of the anthers. This arrangement causes floral visitors to first contact the anthers before the stigma. For this reason, reverse herkogamy is believed to facilitate greater pollen export than approach herkogamy. This type of sex-organ arrangement is typically associated with Lepidopteran Lepidoptera ( ) or lepidopterans is an order ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Distyly
Distyly is a breeding system in plants that is characterized by two separate flower morphs, where individual plants produce flowers that have either long styles and short stamens (L-morph flowers) or short styles and long stamens (S-morph flowers). However, distyly can refer to any plant that shows some degree of Self-incompatibility#/Sporophytic self-incompatibility SSI, self-incompatibility and has two morphs if at least one of the following characteristics is true; there is a difference in Stigma (botany)#/Style, style length, Stamen#/Morphology and terminology, filament length, pollen size or shape, or the surface of the Stigma (botany), stigma. Specifically these plants exhibit intra-morph self-incompatibility, flowers of the same style morph are incompatible. Distylous species that do not exhibit true self-incompatibility generally show a bias towards inter-morph crosses - meaning they exhibit higher success rates when reproducing with an individual of the opposite morph. Dis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Charles Darwin
Charles Robert Darwin ( ; 12 February 1809 – 19 April 1882) was an English Natural history#Before 1900, naturalist, geologist, and biologist, widely known for his contributions to evolutionary biology. His proposition that all species of life have descended from a Common descent, common ancestor is now generally accepted and considered a fundamental scientific concept. In a joint presentation with Alfred Russel Wallace, he introduced his scientific theory that this Phylogenetics, branching pattern of evolution resulted from a process he called natural selection, in which the struggle for existence has a similar effect to the artificial selection involved in selective breeding.. Darwin has been described as one of the most influential figures in human history and was honoured by Burials and memorials in Westminster Abbey, burial in Westminster Abbey. Darwin's early interest in nature led him to neglect his medical education at the University of Edinburgh Medical Schoo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Autogamy
Autogamy or self-fertilization refers to the Cell fusion, fusion of two gametes that come from one individual. Autogamy is predominantly observed in the form of self-pollination, a Reproduction, reproductive mechanism employed by many flowering plants. However, species of protists have also been observed using autogamy as a means of reproduction. Flowering plants engage in autogamy regularly, while the protists that engage in autogamy only do so in stressful environments. Occurrence Protists ''Paramecium aurelia'' ''Paramecium aurelia'' is the most commonly studied protozoan for autogamy. Similar to other unicellular organisms, ''Paramecium aurelia'' typically reproduce asexually via Fission (biology), binary fission or sexually via cross-fertilization. However, studies have shown that when put under nutritional stress, ''Paramecium aurelia'' will undergo meiosis and subsequent fusion of Gamete, gametic-like nuclei. This process, defined as hemixis, a chromosomal rearrangement pro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxalidaceae
The Oxalidaceae, or wood sorrel family, are a small family of five genera of herbaceous plants, shrubs and small trees, with the great majority of the 570 species in the genus ''Oxalis'' (wood sorrels). Members of this family typically have divided leaf, leaves, the leaflets showing "sleep movements", spreading open in light and closing in darkness. The genus ''Averrhoa'' of which starfruit is a member, is usually included in this family (e.g. APG IV, 2016), but some botanists place it in a separate family, Averrhoaceae. References External links OxalidaceaeaniL. Watson and M.J. Dallwitz (1992 onwards). The families of flowering plants: descriptions, illustrations, identification, information retrieval. http://delta-intkey.com * * Oxalidaceae, Rosid families {{Oxalidales-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stamen
The stamen (: stamina or stamens) is a part consisting of the male reproductive organs of a flower. 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 sporangium, microsporangia. Most commonly, anthers are two-lobed (each lobe is termed a locule) and are attached to the filament either at the base or in the middle area of the anther. The sterile (i.e. nonreproductive) tissue between the lobes is called the Connective (botany), 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 in the microsporangium and contains the male gametophyte. The size of anthers differs greatly, from a tiny fraction of a millimeter in ''Wolfia'' spp up to five inches (13 centimeters) in ''Canna iridiflora'' and ''Strelitzia nicolai''. The stamens in a flower ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amaryllidaceae
The Amaryllidaceae are a family of herbaceous, mainly perennial and bulbous (rarely rhizomatous) flowering plants in the monocot order Asparagales. The family takes its name from the genus '' Amaryllis'' and is commonly known as the amaryllis family. The leaves are usually linear, and the flowers are usually bisexual and symmetrical, arranged in umbels on the stem. The petals and sepals are undifferentiated as tepals, which may be fused at the base into a floral tube. Some also display a corona. Allyl sulfide compounds produce the characteristic odour of the onion subfamily (Allioideae). The family, which was originally created in 1805, now contains about 1600 species, divided into 71 genera, 17 tribes and three subfamilies, the Agapanthoideae ('' Agapanthus''), Allioideae ( onions, garlic and chives) and Amaryllidoideae ( amaryllis, daffodils, snowdrops). Over time, it has seen much reorganisation and at various times was combined with the related Liliaceae. Sin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Connaraceae
Connaraceae is a pan-tropical plant family of 19 genera and more than 180 species of largely evergreen trees, woody shrubs and climbers. The family was first described by Robert Brown in 1816 and the name has been conserved. Distribution Connaraceae is a tropical family, the most important genera of which, '' Connarus'' (approximately 80 species) and '' Rourea'' (40-70 species) have a pan-tropical distribution. Their habitat is generally lowland tropical rain forest and savanna. Description Connaraceae are typically evergreen trees, shrubs or climbers. ''Connarus'' is represented by species in all three lifeforms, while ''Rourea'' species are climbers. Their leaves are pinnate, trifoliate or rarely entire, alternate, without stipules and with a pulvinus at the base of the petiole. ''Connarus guianensis'' is economically important for its decorative wood, zebra wood. Genera Fossil record Fossil leaflet impression described as ''Rourea miocaudata'' from India shows close res ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
