1.
Stamen Grigorov
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Stamen Grigorov was a prominent Bulgarian physician and microbiologist, who was the creator of anti-tuberculosis vaccine. He discovered the Lactobacillus bulgaricus bacillus, which is the cause for the existence of natural yogurt. Stamen Grigorov was born in the village of Studen Izvor, Tran, Pernik Province and he completed his secondary education in natural sciences in Montpellier, France and medical science in Geneva, Switzerland. In 1905, at the age of 27, Dr. Grigorov made the discovery, in the microbiological laboratory of Professor Léon Massol in Geneva, he discovered that a certain strain of bacillus is the true cause for the existence of natural yogurt. In recognition the strain was called by the scientific community Lactobacillus bulgaricus, yogurt in its original variety can be produced only in Bulgaria and in some neighboring regions on the Balkan peninsula. In other natural conditions the bacteria quickly degenerate, lose their qualities. Apart from the discovery of Lactobacillus bulgaricus, Dr. Grigorov made a contribution to the creation of an anti-tuberculosis vaccine. On 20 December 1906, in Paris in issue No, after the publication, the scientific community expressed serious interest in Dr. Grigorov’s vaccine. Grigorov Glacier on Brabant Island in Palmer Archipelago, Antarctica is named after Stamen Grigorov, www. stamengrigorov. org В началото бе родовата памет. Фондация Д-р Стамен Григоров, София,2005
2.
Antheridium
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An antheridium is a haploid structure or organ producing and containing male gametes. The plural form is antheridia, and a structure containing one or more antheridia is called an androecium, androecium is also used as the collective term for the stamens of flowering plants. Antheridia are present in the phase of cryptogams like bryophytes. Many algae and some fungi, for example ascomycetes and water moulds, in gymnosperms and angiosperms, the male gametophytes have been reduced to pollen grains and in most of these the antheridia have been reduced to a single generative cell within the pollen grain. During pollination, this cell divides and gives rise to sperm cells. The female counterpart to the antheridium in cryptogams is the archegonium, an antheridium typically consists of sterile cells and spermatogenous tissue. The sterile cells may form a support structure or surround the spermatogenous tissue as a protective jacket. The spermatogenous cells give rise to spermatids via mitotic cell division, in some bryophytes, the antheridium is borne on an antheridiophore, a stalk-like structure that carries the antheridium at its apex. Hornworts have antheridia, in some cases arranged within androecia, microsporangia produce spores that give rise to male gametophytes. National council for Science and the Environment
3.
Hippeastrum
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Hippeastrum /ˌhɪpiːˈæstrəm/ is a genus of about 90 species and over 600 hybrids and cultivars of perennial herbaceous bulbous plants. They generally have large fleshy bulbs and tall broad leaves, generally evergreen, Hippeastrum is a genus in the family Amaryllidaceae The name Hippeastrum, given to it by William Herbert, means Knights-star-lily, although precisely what Herbert meant by the name is not certain. By contrast the generic name Amaryllis applies to bulbs from South Africa, the genus is native to tropical and subtropical regions of the Americas from Argentina north to Mexico and the Caribbean. Reproduction is generally by allogamy and Hippeastrum may be propagated by seed or offset bulbils, although commercial ventures use in vitro techniques, the genus has been intensely bred and cultivated since the early nineteenth century to produce large colourful showy flowers. In temperate climes these can be placed outside in the summer, the bulbs are generally between 5–12 cm in diameter and produce two to seven long-lasting evergreen or deciduous leaves that are 30–90 cm long and 2. 5–5 cm wide. The leaves are hysteranthous, sessile, rarely persistent and subpetiolate, depending on the species, there are two to fifteen large showy flowers, which are more or less zygomophic and hermaphrodite. Each flower is 13–20 cm across, and the species are usually purple or red. They are funnelform and declinate in shape, the perianth has six brightly colored tepals that may be similar in appearance or very different. The perianth segments are subequal or unequal, the tepals are united at the base to form a short tube, usually with a rudimentary scaly paraperigonium with fimbriae or a callose ridge present at the throat. The androecium consists of six stamens with filiform filaments, which are fasciculate and declinate or ascendent, the anthers are dorsifixed or versatile. In the gynaecium, the ovary is inferior and trilocular with pluriovulate locules, the style is filiform, and the stigma trifid. The taxonomy of the genus is complicated, the first issue is whether the name should more properly be Amaryllis L. In 1753 Carl Linnaeus created the name Amaryllis belladonna, the species of the genus Amaryllis. Linnaeus had earlier worked on the Estate of George Clifford near Haarlem between 1735 and 1737 describing the plants growing there in his Hortus Cliffortianus in 1738 and it is to this work that he refers in his Species Plantarum. This was assumed to be the South African Cape Belladonna, although not precisely known, cliffords herbarium is now preserved at the Natural History Museum in London. At the time both South African and South American plants were placed in this same genus and this work commenced in 1819 with the contributions of the English botanist, the Revd. William Herbert in Curtiss Botanical Magazine which he expanded in 1821 in The Botanical Register, identifying 14 species of the new genus of Hippeastrum, the rest of the Amaryllis species he transferred to other genera, several of which he created. Herbert further refined his descriptions of Hippeastrum in his work on the Amaryllidaceae in 1837, since then a key question has been whether Linnaeuss original type was a South African plant or a South American plant
4.
Pollen
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Pollen is a fine to coarse powdery substance comprising pollen grains which are male microgametophytes of seed plants, which produce male gametes. If pollen lands on a compatible pistil or female cone, it germinates, individual pollen grains are small enough to require magnification to see detail. The study of pollen is called palynology and is useful in paleoecology, paleontology, archaeology. Pollen in plants is used for transferring haploid male genetic material from the anther of a flower to the stigma of another in cross-pollination. In a case of self-pollination, this takes place from the anther of a flower to the stigma of the same flower. Pollen itself is not the male gamete, each pollen grain contains vegetative cells and a generative cell. In flowering plants the vegetative tube cell produces the pollen tube, pollen is produced in the microsporangia in the male cone of a conifer or other gymnosperm or in the anthers of an angiosperm flower. Pollen grains come in a variety of shapes, sizes. Pollen grains of pines, firs, and spruces are winged, the smallest pollen grain, that of the forget-me-not, is around 6 µm in diameter. Wind-borne pollen grains can be as large as about 90–100 µm, in angiosperms, during flower development the anther is composed of a mass of cells that appear undifferentiated, except for a partially differentiated dermis. As the flower develops, four groups of cells form within the anther. The fertile sporogenous cells are surrounded by layers of cells that grow into the wall of the pollen sac. Some of the cells grow into nutritive cells that supply nutrition for the microspores that form by meiotic division from the sporogenous cells, in a process called microsporogenesis, four haploid microspores are produced from each diploid sporogenous cell, after meiotic division. After the formation of the four microspores, which are contained by callose walls, the exine is what is preserved in the fossil record. Two basic types of microsporogenesis are recognised, simultaneous and successive, in simultaneous microsporogenesis meiotic steps I and II are completed prior to cytokinesis, whereas in successive microsporogenesis cytokinesis follows. While there may be a continuum with intermediate forms, the type of microsporogenesis has systematic significance, the predominant form amongst the monocots is successive, but there are important exceptions. During microgametogenesis, the unicellular microspores undergo mitosis and develop into mature microgametophytes containing the gametes, in some flowering plants, germination of the pollen grain may begin even before it leaves the microsporangium, with the generative cell forming the two sperm cells. Except in the case of submerged aquatic plants, the mature pollen grain has a double wall
5.
Reproductive organ
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The external and visible organs, in males and females, are the primary sex organs known as the genitals or genitalia. The internal organs are known as the sex organs and are sometimes referred to as the internal genitalia. The characteristics that begin to appear during puberty, such as, in humans, mosses, ferns, and some similar plants have gametangia for reproductive organs, which are part of the gametophyte. The flowers of flowering plants produce pollen and egg cells, but the sex organs themselves are inside the gametophytes within the pollen, coniferous plants likewise produce their sexually reproductive structures within the gametophytes contained within the cones and pollen. The cones and pollen are not themselves sexual organs, the other, hidden sex organs are referred to as the secondary sex organs or internal genitalia. The most important of these are the gonads, a pair of sex organs, gonads are the true sex organs, generating reproductive gametes containing inheritable DNA. They also produce most of the hormones that affect sexual development. The visible portion of the genitals for males consists of the scrotum and penis, for females, it consists of the vulva. In placental mammals, females have two genital orifices, the vagina and urethra, while males have one, the urethra. Male and female genitals have many nerve endings, resulting in pleasurable, in most human societies, particularly in conservative ones, exposure of the genitals is considered a public indecency. In mammals, sex organs include, In typical prenatal development, sexual organs originate from a common anlage anatomy during early gestation, the SRY gene, usually located on the Y chromosome and encoding the testis determining factor, determines the direction of this differentiation. The absence of it allows the gonads to continue to develop into ovaries, thereafter, the development of the internal reproductive organs and the external genitalia is determined by hormones produced by certain fetal gonads and the cells response to them. The initial appearance of the fetal genitalia looks basically feminine, a pair of urogenital folds with a protuberance in the middle. Each sexual organ in one sex has a counterpart in the other one. See a list of homologues of the reproductive system. Furthermore, differences in brain structure arise, affecting, but not absolutely determining, intersex is the development of genitalia somewhere between typical male and female genitalia. Some parents allow their doctors to choose, if they do decide to modify the genitalia, they have approximately a 50% chance of getting genitalia that will match the childs gender identity. If they pick the one, their child may begin to show symptoms of transsexualism
6.
Flower
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A flower, sometimes known as a bloom or blossom, is the reproductive structure found in plants that are floral. The biological function of a flower is to effect reproduction, usually by providing a mechanism for the union of sperm with eggs, Flowers may facilitate outcrossing or allow selfing. Some flowers produce diaspores without fertilization, Flowers contain sporangia and are the site where gametophytes develop. Many flowers have evolved to be attractive to animals, so as to them to be vectors for the transfer of pollen. After fertilization, the ovary of the flower develops into fruit containing seeds, the essential parts of a flower can be considered in two parts, the vegetative part, consisting of petals and associated structures in the perianth, and the reproductive or sexual parts. A stereotypical flower consists of four kinds of structures attached to the tip of a short stalk, each of these kinds of parts is arranged in a whorl on the receptacle. The four main whorls are as follows, Collectively the calyx, corolla, the next whorl toward the apex, composed of units called petals, which are typically thin, soft and colored to attract animals that help the process of pollination. Androecium, the whorl, consisting of units called stamens. Stamens consist of two parts, a called a filament, topped by an anther where pollen is produced by meiosis. Gynoecium, the innermost whorl of a flower, consisting of one or more units called carpels, the carpel or multiple fused carpels form a hollow structure called an ovary, which produces ovules internally. Ovules are megasporangia and they in turn produce megaspores by meiosis which develop into female gametophytes and these give rise to egg cells. The gynoecium of a flower is described using an alternative terminology wherein the structure one sees in the innermost whorl is called a pistil. A pistil may consist of a carpel or a number of carpels fused together. The sticky tip of the pistil, the stigma, is the receptor of pollen, the supportive stalk, the style, becomes the pathway for pollen tubes to grow from pollen grains adhering to the stigma. The relationship to the gynoecium on the receptacle is described as hypogynous, perigynous, although the arrangement described above is considered typical, plant species show a wide variation in floral structure. These modifications have significance in the evolution of flowering plants and are used extensively by botanists to establish relationships among plant species, the four main parts of a flower are generally defined by their positions on the receptacle and not by their function. Many flowers lack some parts or parts may be modified into other functions and/or look like what is typically another part, in some families, like Ranunculaceae, the petals are greatly reduced and in many species the sepals are colorful and petal-like. Other flowers have modified stamens that are petal-like, the flowers of Peonies and Roses are mostly petaloid stamens
7.
Sporangium
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A sporangium is an enclosure in which spores are formed. It can be composed of a cell or can be multicellular. All plants, fungi, and many other lineages form sporangia at some point in their life cycle, sporangia can produce spores by mitosis, but in nearly all land plants and many fungi, sporangia are the site of meiosis and produce genetically distinct haploid spores. Structure containing the spores in fungal species, in mosses, liverworts and hornworts, an unbranched sporophyte produces a single sporangium, which may be quite complex morphologically. Most non-vascular plants, as well as many lycophytes and most ferns, are homosporous, some bryophytes, most lycophytes, and some ferns are heterosporous. These plants produce microspores and megaspores, which rise to gametophytes that are functionally male or female. In some cases, both kinds of spores are produced in the sporangium, and may even develop together as part of a spore tetrad. However, in most heterosporous plants there are two kinds of sporangia, termed microsporangia and megasporangia, a few ferns and some lycophytes are heterosporous with two kinds of sporangia, as are all the seed plants. Sporangia can be terminal or lateral of stems or associated with leaves, in ferns, sporangia are typically found on the abaxial surface of the leaf and are densely aggregated into clusters called sori. Sori may be covered by a structure called an indusium, some ferns have their sporangia scattered along reduced leaf segments or along the margin of the leaf. Lycophytes, in contrast, bear their sporangia on the surface of leaves or laterally on stems. Leaves that bear sporangia are called sporophylls, if the plant is heterosporous, the sporangia-bearing leaves are distinguished as either microsporophylls or megasporophylls. In seed plants, sporangia are located within strobili or flowers. Cycads form their microsporangia on microsporophylls which are aggregated into strobili, megasporangia are formed within ovules, which are borne on megasporophylls, which are aggregated into strobili on separate plants. Conifers typically bear their microsporangia on microsporophylls aggregated into pollen strobili. Flowering plants contain microsporangia in the anthers of stamens and megasporangia inside ovules inside ovaries, in all seed plants, spores are produced by meiosis and develop into gametophytes while still inside the sporangium. Categorized based on sequence, eusporangia and leptosporangia are differentiated in the vascular plants. In a leptosporangium, found only in ferns, development involves a single cell that becomes the stalk, wall
8.
Microspore
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Microspores are land plant spores that develop into male gametophytes, whereas megaspores develop into female gametophytes. The male gametophyte gives rise to cells, which are used for fertilization of an egg cell to form a zygote. Microspores are structures that are part of the alternation of generations in many seedless vascular cryptogams, all gymnosperms, plants with heterosporous life cycles using microspores and megaspores arose independently in several plant groups during the Devonian period. Microspores are haploid, and are produced from microsporocytes by meiosis. This process is the most effective way of yielding haploid and double haploid plants through the use of sex hormones. In the anther, after a microspore undergoes microsporogenesis, it can deviate towards embryogenesis, the microspore can then go one of four ways, Become an embryogenic microspore, undergo callogenesis to organogenesis, become a pollen-like structure or die. The microspore consists of three different walled layers, the outer layer is called the perispore, the next is the exospore, and the inner layer is the endospore. The perispore is the thickest of the three layers while the exospore and endospore are relatively equal in width, microsporophylls bear microsporangia containing many microsporocytes that undergo meiosis, producing tiny microspores. Each microspore may become a male gametophyte consisting of a somewhat spherical antheridium within the microspore wall, either 128 or 256 sperm cells with flagella are produced in each antheridium. In the ferns, the only heterosporous plants are aquatic or semi-aquatic, including the genera Marsilea, Regnellidium, Pilularia, Salvinia and this condition is also known in the lycopod genus Selaginella and in the quillwort genus Isoëtes. Types of seedless vascular plants, Ferns Spikemosses Quillworts In seed plants the microspores are the first cells to form into the male gametophyte, the megaspores, in turn, are formed within the developing seed. Pollen cones usually develop toward the tips of the branches in clusters up to 50 or more. Microsporangia develop in pairs toward the bases of the scales, each of the microsporocytes in the microsporangia undergoes meiosis, producing four haploid microspores. These develop into pollen grains, each consists of four cells. The air sacs give the pollen grains added buoyancy that could help with wind dispersal, types of Gymnosperms, Conifers Pines Ginkgos Cycads Gnetophytes As the anther of a flowering plant develops, four patches of tissue differentiate from the main mass of cells. These patches of tissue contain many diploid microsporocyte cells, each of which undergoes meiosis producing a quartet of microspores, four chambers lined with nutritive tapetal cells are visible by the time the microspores are produced. After meiosis, the haploid microspores undergo several changes, The microspore divides by mitosis producing two cells, the first of the cells is small and is formed inside the second larger cell. The members of each part of the microspores separate from each other, a double-layered wall then develops around each microspore
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Rendle, Alfred Barton (1911). "Flower". In Chisholm, Hugh. Encyclopædia Britannica. 10 (11th ed.). Cambridge University Press. pp. 553–573.
Rendle, Alfred Barton (1911). "
