|
Cross-pollination
Xenogamy (Greek ''xenos''=stranger, ''gamos''=marriage) is the transfer of pollen grains from the anther to the stigma of a different plant. This is the only type of cross pollination which during pollination brings genetically different types of pollen grains to the stigma. The term xenogamy (along with geitonogamy and autogamy) was first suggested by Kerner in 1876.{{cite book, last=Darwin, first=Charles, title=More Letters of Charles Darwin, Volume 2, date=August 2006, publisher=Echo Library, isbn=978-1-4068-0482-9 , url=https://books.google.com/books?id=X9vMhLOiTmQC&dq=Xenogamy&pg=PA668, access-date=25 February 2012, page=668 Cross-pollination involves the transfer of pollen grains from the flower of one plant to the stigma of the flower of another plant. The main characteristics which facilitate cross-pollination are: * Herkogamy: Flowers possess some mechanical barrier on their stigmatic surface to avoid self-pollination, e.g. presence of gynostegium and pollinia in '' C ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pollination
Pollination is the transfer of pollen from an anther of a plant to the stigma (botany), stigma of a plant, later enabling fertilisation and the production of seeds. Pollinating agents can be animals such as insects, for example bees, beetles or butterflies; birds, and bats; water; wind; and even plants themselves. Pollinating animals travel from plant to plant carrying pollen on their bodies in a vital interaction that allows the transfer of genetic material critical to the reproductive system of most flowering plants. Self-pollination occurs within a closed flower. Pollination often occurs within a species. When pollination occurs between species, it can produce hybrid (biology), hybrid offspring in nature and in plant breeding work. In angiosperms, after the pollen grain (gametophyte) has landed on the stigma (botany), stigma, it germinates and develops a pollen tube which grows down the style (botany), style until it reaches an ovary (botany), ovary. Its two gametes travel down ... [...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 temporal ( 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. Mec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pollen Grain
Pollen is a powdery substance produced by most types of flowers of seed plants for the purpose of sexual reproduction. 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 ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geitonogamy
Geitonogamy (from Greek ''geiton'' (γείτων) = neighbor + ''gamein'' (γαμεῖν) = to marry) is a type of self-pollination. Geitonogamous pollination is sometimes distinguished from the fertilizations that can result from it, geitonogamy. If a plant is self-incompatible, geitonogamy can reduce seed production. Geitonogamy is when pollen is exported using a vector (pollinator or wind) out of one flower but only to another flower on the same plant. It is a form of self-fertilization. In flowering plants, pollen is transferred from a flower to another flower on the same plant, and in animal pollinated systems this is accomplished by a pollinator visiting multiple flowers on the same plant. Geitonogamy is also possible within species that are wind-pollinated, and may actually be a quite common source of self-fertilized seeds in self-compatible species. It also occurs in monoecious gymnosperms. Although geitonogamy is functionally cross-pollination involving a pollinating ag ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stigma (botany)
The stigma (: stigmas or stigmata) is the receptive tip of a Gynoecium#Carpels, carpel, or of several fused carpels, in the gynoecium of a flower. Description The stigma, together with the Style (botany), style and ovary (botany), ovary (typically called the stigma-style-ovary system) comprises the pistil, which is part of the gynoecium or female reproductive organ of a plant. The stigma itself forms the distal portion of the style, or stylodia, and is composed of , the cells of which are receptive to pollen. These may be restricted to the apex of the style or, especially in wind pollinated species, cover a wide surface. The stigma receives pollen and it is on the stigma that the pollen grain germination, germinates. Often sticky, the stigma is adapted in various ways to catch and trap pollen with various hairs, flaps, or sculpturings. The pollen may be captured from the air (wind-borne pollen, anemophily), from visiting insects or other animals (Pollination syndrome#Biotic, ... [...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] |
Anton Kerner Von Marilaun
Anton Kerner Ritter von Marilaun, or Anton Joseph Kerner, (12 November 1831 – 21 June 1898) was an Austrian botanist, physician, and professor at the University of Innsbruck and later at the University of Vienna. Von Marilaun emphasized the concept of plant sociology or the species that plants were typically found associated with in his geographical studies of species. Inspired by the work of Alexander von Humboldt and others he examined climatological and historical factors in the distributions of plant species. Career Kerner was born in Mautern, Lower Austria, and studied medicine in Vienna, graduating in 1854 with a medical degree. He also studied the flora of Wachau. He then became a teacher at Often and continued his studies in natural history. In 1858 Kerner was appointed professor of botany at the Polytechnic Institute at Buda, and then in 1860 was appointed professor of natural history at the University of Innsbruck. During this period he carried out phytosociology, ph ... [...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] |
Calotropis
''Calotropis'' is a genus of flowering plants in the family Apocynaceae, first described as a genus in 1810. It is native to southern Asia and North Africa. They are commonly known as milkweeds because of the latex they produce. ''Calotropis'' species are considered common weeds in some parts of the world. The flowers are fragrant and are often used in making floral tassels in some mainland Southeast Asian cultures. Fibers of these plants are called madar or mader. ''Calotropis'' species are usually found in abandoned farmland. Botanical description ''Calotropis gigantea'' and ''C. procera'' are the two most common species in the genus. Both plants can attain an average height of although they can occasionally become as tall as . The leaves are sessile and sub-sessile, opposite, ovate, cordate at the base. The flowers are about in size, with umbellate lateral cymes and are colored white to pink and are fragrant in case of ''C. procera'' while the flowers of ''C. gigantea'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dichogamy
Sequential hermaphroditism (called dichogamy in botany) is one of the two types of hermaphroditism, the other type being simultaneous hermaphroditism. It occurs when the organism's sex changes at some point in its life. A sequential hermaphrodite produces eggs (female gametes) and sperm (male gametes) at different stages in life. Sequential hermaphroditism occurs in many fish, gastropods, and plants. Species that can undergo these changes do so as a normal event within their reproductive cycle, usually cued by either social structure or the achievement of a certain age or size. In animals, the different types of change are male to female (protandry or protandrous hermaphroditism), female to male (protogyny or protogynous hermaphroditism), and bidirectional (serial or bidirectional hermaphroditism). Both protogynous and protandrous hermaphroditism allow the organism to switch between functional male and functional female. Bidirectional hermaphrodites have the capacity for sex chan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plant Sexuality
Plant reproductive morphology is the study of the physical form and structure (the morphology) of those parts of plants directly or indirectly concerned with sexual reproduction. Among all living organisms, flowers, which are the reproductive structures of angiosperms, are the most varied physically and show a correspondingly great diversity in methods of reproduction. Plants that are not flowering plants ( green algae, mosses, liverworts, hornworts, ferns and gymnosperms such as conifers) also have complex interplays between morphological adaptation and environmental factors in their sexual reproduction. The breeding system, or how the sperm from one plant fertilizes the ovum of another, depends on the reproductive morphology, and is the single most important determinant of the genetic structure of nonclonal plant populations. Christian Konrad Sprengel (1793) studied the reproduction of flowering plants and for the first time it was understood that the pollination pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dioecious
Dioecy ( ; ; adj. dioecious, ) is a characteristic of certain species that have distinct unisexual individuals, each producing either male or female gametes, either directly (in animals) or indirectly (in seed plants). Dioecious reproduction is biparental reproduction. Dioecy has costs, since only the female part of the population directly produces offspring. It is one method for excluding self-fertilization and promoting allogamy (outcrossing), and thus tends to reduce the expression of recessive deleterious mutations present in a population. Plants have several other methods of preventing self-fertilization including, for example, dichogamy, herkogamy, and self-incompatibility. In zoology In zoology, dioecy means that an animal is either male or female, in which case the synonym gonochory is more often used. Most animal species are gonochoric, almost all vertebrate species are gonochoric, and all bird and mammal species are gonochoric. Dioecy may also describe colonies ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
