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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 t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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] |
Distyly
Distyly is a type of heterostyly in which a plant demonstrates reciprocal herkogamy. This breeding system is characterized by two separate flower morphs, where individual plants produce flowers that either have long styles and short stamens (L-morph flowers), or that have short styles and long stamens (S-morph flowers). However, distyly can refer to any plant that shows some degree of self-incompatibility and has two morphs if at least one of the following characteristics is true; there is a difference in style length, filament length, pollen size or shape, or the surface of the 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. Background The first scientific account of distyly can be f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Self-incompatibility In Plants
Self-incompatibility (SI) is a general name for several genetic mechanisms that prevent self-fertilization in sexually reproducing organisms, and thus encourage outcrossing and allogamy. It is contrasted with separation of sexes among individuals (dioecy), and their various modes of spatial ( herkogamy) and temporally (dichogamy) separation. SI is best-studied and particularly common in flowering plants, although it is present in other groups, including sea squirts and fungi. In plants with SI, when a pollen grain produced in a plant reaches a stigma of the same plant or another plant with a matching allele or genotype, the process of pollen germination, pollen-tube growth, ovule fertilization, or embryo development is inhibited, and consequently no seeds are produced. SI is one of the most important means of preventing inbreeding and promoting the generation of new genotypes in plants and it is considered one of the causes of the spread and success of angiosperms on Earth. Mech ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Primula
''Primula'' () is a genus of herbaceous flowering plants in the family Primulaceae. They include the primrose ('' P. vulgaris''), a familiar wildflower of banks and verges. Other common species are '' P. auricula'' (auricula), '' P. veris'' (cowslip), and '' P. elatior'' (oxlip). These species and many others are valued for their ornamental flowers. They have been extensively cultivated and hybridised (in the case of the primrose, for many hundreds of years). ''Primula'' are native to the temperate Northern Hemisphere, south into tropical mountains in Ethiopia, Indonesia, and New Guinea, and in temperate southern South America. Almost half of the known species are from the Himalayas. ''Primula'' has over 500 species in traditional treatments, and more if certain related genera are included within its circumscription.''Primula''. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heteromorphic Self-incompatibility
Self-incompatibility (SI) is a general name for several genetic mechanisms that prevent self-fertilization in sexually reproducing organisms, and thus encourage outcrossing and allogamy. It is contrasted with separation of sexes among individuals ( dioecy), and their various modes of spatial (herkogamy) and temporally (dichogamy) separation. SI is best-studied and particularly common in flowering plants, although it is present in other groups, including sea squirts and fungi. In plants with SI, when a pollen grain produced in a plant reaches a stigma of the same plant or another plant with a matching allele or genotype, the process of pollen germination, pollen-tube growth, ovule fertilization, or embryo development is inhibited, and consequently no seeds are produced. SI is one of the most important means of preventing inbreeding and promoting the generation of new genotypes in plants and it is considered one of the causes of the spread and success of angiosperms on Earth. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polymorphism (biology)
In biology, polymorphism is the occurrence of two or more clearly different morphs or forms, also referred to as alternative ''phenotypes'', in the population of a species. To be classified as such, morphs must occupy the same habitat at the same time and belong to a panmictic population (one with random mating). Ford E.B. 1965. ''Genetic polymorphism''. Faber & Faber, London. Put simply, polymorphism is when there are two or more possibilities of a trait on a gene. For example, there is more than one possible trait in terms of a jaguar's skin colouring; they can be light morph or dark morph. Due to having more than one possible variation for this gene, it is termed 'polymorphism'. However, if the jaguar has only one possible trait for that gene, it would be termed "monomorphic". For example, if there was only one possible skin colour that a jaguar could have, it would be termed monomorphic. The term polyphenism can be used to clarify that the different forms arise from the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pontederiaceae
Pontederiaceae is a 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 monocots. It is a small family of heterostylous aquatic plants, occurring in tropical and 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 ('' Pontederia crassipes''), which is an invasive species in many waterways. The highly modified '' Heteranthera gardneri'' is a submerged aquatic with a two-flowered pseudanthium. Taxonomy The two genera within this family are: *'' Heteranthera'' Ruiz & Pav. (including '' Eurystemon'', '' Hydrothrix'', '' Scholleropsis'', and '' Zosterella'') *''Pontederia'' L. (inclu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxalis Pes-caprae
''Oxalis pes-caprae'' (African wood-sorrel, Bermuda buttercup, Bermuda sorrel, buttercup oxalis, Cape sorrel, English weed, goat's-foot, sourgrass, soursob or soursop; ) is a species of tristylous yellow-flowering plant in the wood sorrel family Oxalidaceae. ''Oxalis cernua'' is a less common synonym for this species. Some of the most common names for the plant reference its sour taste owing to oxalic acid present in its tissues. Indigenous to South Africa, the plant has become a pest plant in different parts of the world that is difficult to eradicate because of how it propagates through underground bulbs. Name ''Oxalis pes-caprae'' is often called by the common name ''sour''grass due to its moderately sour flavor. This sourness is caused by an exceptionally high content of oxalic acid. The specific epithet ''pes-caprae'' means 'goat's-foot', possibly in reference to the shape of the leaf. Description The ''Oxalis pes-caprae'' flower is actinomorphic, with a calyx ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 gametophytes during the process of their movement from the stamens to the pistil of flowering plants, or from the male cone to the female cone of gymnosperms. If pollen lands on a compatible pistil or female cone, it germinates, producing a pollen tube that transfers the sperm to the ovule containing the female gametophyte. Individual pollen grains are small enough to require magnification to see detail. The study of pollen is called palynology and is highly useful in paleoecology, paleontology, archaeology, and forensics. Pollen in plants is used for transferring haploid male genetic material from the anther of a single flower to the stigma of another in cross-pollination. In a case of self-pollination, this process takes place from the an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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. Processes such as insemination or pollination which happen before the fusion of gametes are also sometimes informally called fertilisation. The cycle of fertilisation and development of new individuals is called sexual reproduction. During double fertilisation in angiosperms the haploid male gamete combines with two haploid polar nuclei to form a triploid primary endosperm nucleus by the process of vegetative fertilisation. History In Antiquity, Aristotle conceived the formation of new individuals through fusion of male and female fluids, with form and function emerging gradually, in a mode called by him as epigenetic. In 1784, Spallanzani established the need of interaction between the female's ovum and male's sperm to form a zygote in fr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eichhornia Azurea6
''Eichhornia'', commonly called water hyacinths, was a polyphyletic genus of the aquatic flowering plants family Pontederiaceae. Since it was consistently recovered in three independent lineages, it has been sunk into ''Pontederia'', together with '' Monochoria''. Each of the three lineages is currently recognized as subgenera in ''Pontederia'': * ''Pontederia'' subg. ''Cabanisia'', which includes '' P. meyeri'', '' P. paniculata'' (the Brazilian water hyacinth), and '' P. paradoxa'' * ''Pontederia'' subg. ''Oshunae'', which includes the common water hyacinth, '' P. crassipes'' * ''Pontederia'' subg. ''Eichhornia'', which includes '' P. azurea'', '' P. diversifolia'', '' P. heterosperma'', and '' P. natans'' ''Pontederia'' subg. ''Eichhornia'' is pantropical, centered in South America but with '' P. natans'' being endemic to continental Africa and Madagascar. The other three species are restricted to the Neotropics. It was named in honour of , an early-19th-century Prussian min ... [...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 leaves A leaf ( : leaves) is any of the principal appendages of a vascular plant stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, st ..., 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 * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
