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Rostellum
The rostellum is a projecting part of the column in Orchidaceae flowers, and separates the male androecium from the female gynoecium, commonly preventing self-fertilisation. In many orchids, such as '' Orchis mascula'', the pollinia or pollen masses, are connected by stipes down to adhesive discs attached to the rostellum which forms cups keeping the discs or balls sticky. In ''Catasetum'' flowers the rostellum projects forward at each side as an "antenna", and the pollen masses are connected by a bent stalk or pedicel to a sticky disc kept moist at the back of the flower. When an insect touches an "antenna", this releases the bent pedicel which springs straight and fires the pollinium, sticky disc first, at the insect. Charles Darwin described in ''Fertilisation of Orchids ''Fertilisation of Orchids'' is a book by English naturalist Charles Darwin published on 15 May 1862 under the full explanatory title ''On the Various Contrivances by Which British and Foreign Orchid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fertilisation Of Orchids Figure 1X
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 fro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Column (botany)
The column, or technically the gynostemium, is a reproductive structure that can be found in several plant families: Aristolochiaceae, Orchidaceae, and Stylidiaceae. It is derived from the fusion of both male and female parts (stamens and pistil) into a single organ. The top part of the column is formed by the anther, which is covered by an anther cap. This means that the ''style'' and ''stigma'' of the pistil, with the filaments and one or more anthers, are all united. Orchidaceae The stigma sits at the apex of the column in the front but is pointing downwards after resupination (the rotation by 180 degrees before unfolding of the flower). This stigma has the form of a small bowl, the clinandrium, a viscous surface embedding the (generally) single anther. On top of it all is the anther cap. Sometimes there is a small extension or little beak to the median stigma lobe, called rostellum. Column wings may project laterally from the stigma. The column foot is formed by the a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orchidaceae
Orchids are plants that belong to the family Orchidaceae (), a diverse and widespread group of flowering plants with blooms that are often colourful and fragrant. Along with the Asteraceae, they are one of the two largest families of flowering plants. The Orchidaceae have about 28,000 currently accepted species, distributed in about 763 genera. (See ''External links'' below). The determination of which family is larger is still under debate, because verified data on the members of such enormous families are continually in flux. Regardless, the number of orchid species is nearly equal to the number of bony fishes, more than twice the number of bird species, and about four times the number of mammal species. The family encompasses about 6–11% of all species of seed plants. The largest genera are ''Bulbophyllum'' (2,000 species), ''Epidendrum'' (1,500 species), ''Dendrobium'' (1,400 species) and ''Pleurothallis'' (1,000 species). It also includes ''Vanilla'' (the genus of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gynoecium
Gynoecium (; ) is most commonly used as a collective term for the parts of a flower that produce ovules and ultimately develop into the fruit and seeds. The gynoecium is the innermost whorl of a flower; it consists of (one or more) ''pistils'' and is typically surrounded by the pollen-producing reproductive organs, the stamens, collectively called the androecium. The gynoecium is often referred to as the "female" portion of the flower, although rather than directly producing female gametes (i.e. egg cells), the gynoecium produces megaspores, each of which develops into a female gametophyte which then produces egg cells. The term gynoecium is also used by botanists to refer to a cluster of archegonia and any associated modified leaves or stems present on a gametophyte shoot in mosses, liverworts, and hornworts. The corresponding terms for the male parts of those plants are clusters of antheridia within the androecium. Flowers that bear a gynoecium but no stamens are cal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orchis Mascula
''Orchis mascula'', the early-purple orchid, early spring orchis, is a species of flowering plant in the orchid family, Orchidaceae. Description ''Orchis mascula'' is a perennial herbaceous plant with stems up to high, green at the base and purple on the apex. The root system consists of two tubers, rounded or ellipsoid. The leaves, grouped at the base of the stem, are oblong-lanceolate, pale green, sometimes with brownish-purple speckles. The inflorescence is long and it is composed of 6 to 20 flowers gathered in dense cylindrical spikes. The flower size is about and the color varies from pinkish-purple to purple. The lateral sepals are ovate-lanceolate and erect, the median one, together with the petals, is smaller and cover the gynostegium. The labellum is three-lobed and convex, with crenulated margins and the basal part clearer and dotted with purple-brown spots. The spur is cylindrical or clavate, horizontal or ascending. The gynostegium is short, with reddish-green ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pollinium
A pollinium (plural pollinia) is a coherent mass of pollen grains in a plant that are the product of only one anther, but are transferred, during pollination, as a single unit. This is regularly seen in plants such as orchids and many species of milkweeds (Asclepiadoideae). Usage of the term differs: in some orchids two masses of pollen are well attached to one another, but in other orchids there are two halves (with two separate viscidia) each of which is sometimes referred to as a pollinium. Most orchids have waxy pollinia. These are connected to one or two elongate stipes, which in turn are attached to a sticky viscidium, a disc-shaped structure that sticks to a visiting insect. Some orchid genera have mealy pollinia. These are tapering into a caudicle (stalk), attached to the viscidium. They extend into the middle section of the column. The pollinarium is a collective term that means either (1) the complete set of pollinia from all the anthers of a flower, as in Asclepiadoideae ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stipe (botany)
In botany, a stipe is a stalk that supports some other structure. The precise meaning is different depending on which taxonomic group is being described. file:Helicteres-Yucatán-Flowers.jpg, The long stipe of a '' Helicteres'' flower. file:Helicteres-Yucatán-Fruits.jpg, remains as each flower forms a fruit. In the case of ferns, the stipe is only the petiole from the rootstock to the beginning of the leaf tissue, or lamina. The continuation of the structure within the lamina is then termed a rachis. In flowering plants, the term is often used in reference to a stalk that sometimes supports a flower's ovary. In orchids, the stipe or caudicle is the stalk-like support of the pollinia. It is a non-viscid band or strap connecting the pollinia with the viscidium (the viscid part of the rostellum or beak). A stipe is also a structure found in organisms that are studied by botanists but that are no longer classified as plants. It may be the stem-like part of the thallus of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Viscidium
A pollinium (plural pollinia) is a coherent mass of pollen grains in a plant that are the product of only one anther, but are transferred, during pollination, as a single unit. This is regularly seen in plants such as orchids and many species of milkweeds (Asclepiadoideae). Usage of the term differs: in some orchids two masses of pollen are well attached to one another, but in other orchids there are two halves (with two separate viscidia) each of which is sometimes referred to as a pollinium. Most orchids have waxy pollinia. These are connected to one or two elongate stipes, which in turn are attached to a sticky viscidium, a disc-shaped structure that sticks to a visiting insect. Some orchid genera have mealy pollinia. These are tapering into a caudicle (stalk), attached to the viscidium. They extend into the middle section of the column. The pollinarium is a collective term that means either (1) the complete set of pollinia from all the anthers of a flower, as in Asclepiadoid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fertilisation Of Orchids Figure 28
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 fro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Catasetum
''Catasetum'', abbreviated as Ctsm. in horticultural trade, is a genus of showy epiphytic Orchids, family Orchidaceae, subfamily Epidendroideae, tribe Cymbidieae, subtribe Catasetinae, with 166 species, many of which are highly prized in horticulture. Species of the genus ''Catasetum'' occur from Mexico to Argentina, including much of Central America, the West Indies, and South America. The largest number of species is in Brazil. Biology They have thick, cigar-shaped pseudobulbs which are clustered. The leaves are pleated in the upper part and deciduous. The pseudobulbs become spiny after the leaves have dropped. The inflorescence is borne on the basis. It consists of very fleshy flowers that are unisexual, which is exceptional for orchids. The colorful male and yellowish-green female flowers are typically situated on different plants, a phenomenon known as dioecy. Which type of flower a plant produces is determined by the conditions under which it grows. Male and female fl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pedicel (botany)
In botany, a pedicel is a stem that attaches a single flower to the inflorescence. Such inflorescences are described as ''pedicellate''. Description Pedicel refers to a structure connecting a single flower to its inflorescence. In the absence of a pedicel, the flowers are described as sessile. Pedicel is also applied to the stem of the infructescence. The word "pedicel" is derived from the Latin ''pediculus'', meaning "little foot". The stem or branch from the main stem of the inflorescence that holds a group of pedicels is called a peduncle. A pedicel may be associated with a bract or bracts. In cultivation In Halloween types of pumpkin or squash plants, the shape of the pedicel has received particular attention because plant breeders are trying to optimize the size and shape of the pedicel for the best "lid" for a "jack-o'-lantern". Gallery File:Asclepias amplexicaulis.jpg, Long pedicels of clasping milkweed with a single peduncle File:314 Prunus avium.jpg, Cherry ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Charles Darwin
Charles Robert Darwin ( ; 12 February 1809 – 19 April 1882) was an English naturalist, geologist, and biologist, widely known for his contributions to evolutionary biology. His proposition that all species of life have descended from a common ancestor is now generally accepted and considered a fundamental concept in science. In a joint publication with Alfred Russel Wallace, he introduced his scientific theory that this 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 burial in Westminster Abbey. Darwin's early interest in nature led him to neglect his medical education at the University of Edinburgh; instead, he helped to investigate marine invertebrates. His studies at the University of Cambridge's Christ's ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
