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ovules

ovules Sentence Examples

  • Vertical section to show the ovules o, attached to the parietes.

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  • Two rows of ovules are seen, one in front and the other in profile.

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  • p, placenta; o, ovules; s, suture, or median line of carpel.

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  • The ovary is generally two-chambered, with two inverted ovules standing side by side at the inner angle of each chamber.

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  • The ovary bears a sessile stigma and is more or less completely two-celled, with two erect ovules in each cell.

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  • In Gymnosperms we have seeds, and the carpels may become modified and close around these, as in Pinus, during the process of ripening to form an imitation of a box-like fruit which subsequently opening allows the seeds to escape; but there is never in them the closed ovary investing from the outset the ovules, and ultimately forming the ground-work of the fruit.

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  • Finally in the yew, as a type of the family Taxeae, the ovules occur singly at the apex of a lateral branch, enclosed when ripe by a conspicuous red or yellow fleshy arillus, which serves as an attraction to animals, and thus aids in the dispersal of the seeds.

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  • These projections and ridges may be homologous with the seminiferous scale of the pines, firs, cedars, &c. The simplest interpretation of the cone of the Abietineae is that which regards it as a flower consisting of an axis bearing several open carpels, which in the adult cone may be very small or large and prominent, the scale bearing the ovules being regarded as a placental outgrowth from the flat and open carpel.

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  • Robert Brown was the first to give a clear description of the morphology of the Abietineous cone in which carpels bear naked ovules; he recognized gymnospermy as an important distinguishing feature in conifers as well as in cycads.

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  • An interesting case has been figured by Masters, in which scales of a cone of Cupressus Lawsoniana bear ovules on the upper surface and stamens on the lower face.

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  • In 1906 he gave an account of the early stages of development of the male and female organs and, among other interesting statements in regard to the general biology of Welwitschia, he expressed the opinion that, as Hooker suspected, the ovules are pollinated by insect-agency.

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  • The ovary bears a sessile stigma and is more or less completely two-celled, with two erect ovules in each cell.

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  • These projections and ridges may be homologous with the seminiferous scale of the pines, firs, cedars, &c. The simplest interpretation of the cone of the Abietineae is that which regards it as a flower consisting of an axis bearing several open carpels, which in the adult cone may be very small or large and prominent, the scale bearing the ovules being regarded as a placental outgrowth from the flat and open carpel.

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  • The spores, as in the heterosporous Pteridophyta, are of two kindsmicrospores (pollen grains) borne in microsporangia (pollen sacs) on special leaves (sporophylls) known as stamens, and macrospores (embryo-sac) borne in macrosporangia (ovules) on sporophylls known as carpels.

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  • In GY~~1NospERMsso-called because the ovules (and seeds) are borne on an open sporophyll or carpelthe microsporophylls and macrosporophylls are not as a rule associated in the same shoot and are generally arranged in cone-like structures; one or two small prothallial cells are formed in the germination of the microspore; the male cells are in some older members of the group motile though usually passive.

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  • The pistil consists of a single carpel with its ovary, style, stigma and solitary ovule or twin ovules.

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  • From the centre, processes (s) go to circumference(t), ending in curved placentaries bearing the ovules.

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  • Both bear their round or ovoid male catkins at the ends of the slender terminal branchlets; the ovoid cones, either terminal or on short lateral twigs, have thick woody scales dilated at the extremity, with a broad disk depressed in the centre and usually furnished with a short spine; at the base of the scales are from three to seven ovules, which become reversed or partially so by compression, ripening into small angular seed with a narrow wing-like expansion.

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  • There are five, or sometimes fewer, carpels, which unite to form an ovary with as many chambers, in each of which are one or two, rarely more, pendulous anatropous ovules, attached to the central column in such a way that the micropyle points outwards and the raphe is turned towards the placenta.

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  • In the simplest instances the pollen of one flower fertilizes the ovules of another on the same plant, owing to the stamens arriving at maturity in any one flower earlier or later than the pistils.

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  • The conidia are fragrant and are carried by bees to the stigma of the bilberry; here they germinate with the pollen and the hyphae pass with the pollen tubes down the style; the former infect the ovules and produce sclerotia, therein reducing the fruits to a mummified condition.

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  • The ovary is incompletely divided into many chambers by the ingrowth of the placentas which bear numerous ovules and form in the fruit a many-seeded short capsule opening by small valves below the upper edge.

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  • The carpel, or aggregate of carpels forming the pistil or gynaeceum, comprises an ovary containing one or more ovules and a receptive surface or stigma; the stigma is sometimes carried up on a style.

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  • The ovary contains one or more ovules borne on a placenta, which is generally some part of the ovary-wall.

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  • The eight series of Monochlamydeae, containing 36 orders, form groups characterized mainly by differences in the ovary and ovules, and are now recognized as of unequal value.

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  • The petaloid perianth consists of two series, each with three members, which are joined below into a longer or shorter tube, followed by one whorl of three stamens; the inferior ovary is three-celled and contains numerous ovules on an axile placenta; the style is branched and the branches are often petaloid.

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  • The superior ovary - half-inferior in Samolus - bears a simple style ending in a capitate entire stigma, and contains a free-central placenta bearing generally a large number of ovules, which are exceptional in the group Gamopetalae in having two integuments.

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  • The order is divided into five tribes by characters based on differences in position of the ovules - which are generally semianatropous so that the seed is peltate with the hilum in the centre on one side (or ventral), but sometimes, as in Hottonia and (From Strasburger's Lehrbuch der Botanik.) FIG.

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  • The numerous male catkins are generally arranged in dense whorls around the bases of the young shoots; the anther-scales, surmounted by a crest-like appendage, shed their abundant pollen by longitudinal slits; the two ovules at the base of the inner side of each fertile cone-scale develop into a pair of winged seeds, which drop from the opening scales when mature - as in the allied genera.

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  • The same characters will distinguish grasses from the other glumiferous orders, Restiaceae, and Eriocaulonaceae, which are besides further removed by their capsular fruit and pendulous ovules.

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  • yvµvos, naked, nrEp,ua, seed) implies, one characteristic of this group is the absence of an ovary or closed chamber containing the ovules.

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  • Ovules naked, rarely without carpellary leaves, usually borne on carpophylls, which assume various forms. The single megaspore enclosed in the nucellus is filled with tissue (prothallus) before fertilization, and contains two or more archegonia, consisting usually of a large egg-cell and a small neck, rarely of an egg-cell only and no neck (Gnetum and Welwitschia).

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  • From the lower part of a carpel are produced several laterally placed ovules, which become bright red or orange on ripening; the bright fleshy seeds, which in some species are as large as a goose's egg, and the tawny spreading carpels produce a pleasing combination of colour in the midst of the long dark-green fronds, which curve gracefully upwards and outwards from the summit of the columnar stem.

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  • I) on the branched or unbranched stem; (b) the growth of the main stem through the female flower; (c) the presence of a prominent single vein in the linear pinnae; (d) the structure of the female flower, which is peculiar in not having the form of a cone, but consists of numerous independent carpels, each of which bears two or more lateral ovules.

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  • - Characterized by the woolly scaleleaves and carpels; the latter terminate in a thick laminar expansion of triangular form, bearing two placental cushions, on which the ovules are situated.

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  • In Cycas revoluta and C. circinalis each leaf-like carpel may produce several laterally attached ovules, but in C. Normanbyana the carpel is shorter and the ovules are reduced to two; this latter type brings us nearer to the carpels of Dioon, in which the flower has the form of a cone, and the distal end of the carpels is longer and more leaf-like than in the other genera of the Zamieae, which are characterized by shorter carpels with thick peltate heads bearing two ovules on the morphologically lower surface.

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  • Pollination in cycads has always been described as anemophilous, but according to recent observations by Pearson on South African species it seems probable that, at least in some cases, the pollen is conveyed to the ovules by animal agency.

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  • It is often stated that fertilization occurs after the ovules have fallen, but it has been demonstrated by Hirase that this occurs while the ovules are still attached to the tree.

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  • The morphology of the female flowers has been variously interpreted by botanists; the peduncle bearing the ovules has been described as homologous with the petiole of a foliage-leaf and as a shoot-structure, the collar-like envelope at the base of the ovules being referred to as a second integument or arillus, or as the representative of a carpel.

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  • The frequent occurrence of more than two pollen-sacs and the equally common occurrence of additional ovules have been regarded by some authors as evidence in favour of the view that ancestral types normally possessed a greater number of these organs than are usually found in the recent species.

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  • 15, D) Sequoia, &c., there are always two sets of bundles; the upper set, having the phloem uppermost, as in the seminiferous scale of Abies or Pinus, are regarded as belonging to the outgrowth from the carpellary scale and specially developed to supply the ovules.

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  • The scales of the upper or middle series each bear one or two erect ovules.

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  • The flowers spring from, or are enclosed in, a spathe, and are unisexual and regular, with generally a calyx and corolla, each of three members; the stamens are in whorls of three, the inner whorls are often barren; the two to fifteen carpels form an inferior ovary containing generally numerous ovules on often large, produced, parietal placentas.

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  • 26, o), which is the lower portion enclosing the ovules destined to become seeds, and the stigma (g), a portion of loose cellular tissue, the receptive surface on which the pollen is deposited, which is either sessile on the apex of the ovary, as in the poppy, or is separated from it by a prolonged portion called the style (s) .

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  • - The pistil of Tobacco (Nicotiana Tabacum), consisting of the ovary o, containing ovules, the style s, and the capitate stigma g.

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  • - Diagrammatic section of a symmetrical pentamerous flower of Stone-crop (Sedum), consisting of five sepals (s), five petals (p) alternating with the sepals, ten stamens (a) in two rows, and five carpels (c) containing ovules.

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  • It consists essentially of two parts, a basal portion forming a chamber, the ovary, containing the ovules attached to a part called the placenta, and an upper receptive portion, the stigma, which is either seated on the ovary (sessile), as in the tulip and poppy, or is elevated on a stalk called the style, interposed between the ovary and stigma.

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  • Each carpel has its own ovary, style (when present), and stigma, and may be regarded as formed by a folded leaf, the upper surface of which is turned inwards towards the axis, and the lower outwards, while from its margins are developed one or more ovules.

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  • In Cycas the carpels are ordinary leaves, with ovules upon their margin.

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  • The ovules are attached to the placenta, which consists of a mass of cellular tissue, through which the nourishing vessels pass to the ovule.

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  • 1 ovules, developing to form Y (g 9), the fruit.

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  • s, Septum; o, ovules, which form a double row in the inner angle of each chamber.

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  • The ovules (o) are attached to a central placenta, formed by the union of the five ventral sutures.

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  • - Diagrammatic section of a five-carpellary ovary, in which the edges of the carpels, bearing the placentas and ovules o, are not folded inwards.

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  • The placentas are parietal, and the ovules appear sessile on the walls of the ovary.

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  • 92, 93), and the ovules appear in the central angle of the loculi.

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  • - Diagrammatic section of a five-carpellary ovary, in which the septa (s) proceed inwards for a certain length, bearing the placentas and ovules (o).

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  • I, Vertical; 2, horizontal section; c, calyx; d, wall of ovary; o, ovules; p, placenta; s, stigma.

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  • From the centre, processes go to circumference, ending in curved placentas bearing the ovules.

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  • The ovules (o) are attached to a free central placenta, which has no connexion with the walls of the ovary.

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  • In Caryophyllaceae, however, while the placenta is free in the centre, there are often traces found at the base of the ovary of the remains of septa, as if rupture had taken place, and, in rare instances, ovules are found on the margins of the carpels.

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  • o, Ovary; p, free central placenta; g, ovules; s, styles.

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  • - The same cut horizontally, and the halves separated so as to show the interior of the cavity of the ovary o, with the free central placenta p, covered with ovules g.

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  • carpellary leaves, and that in the progress of development these leaves separated from them, leaving the placentas and ovules free in the centre; or by supposing that the placentas are not marginal but axile formations, produced by an elongation of the axis, and the carpels verticillate leaves, united together around the axis.

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  • Ovules are most usually produced on the margins of FIG.

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  • The carpellary leaves are sometimes united in such a way as to leave an opening at the apex of the pistil, so that the ovules are exposed, as in mignonette.

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  • In Leontice thalictroides (Blue Cohosh), species of Ophiopogon, Peliosanthes and Stateria, the ovary ruptures immediately after flowering, and the ovules are exposed; and in species of Cuphea the placenta ultimately bursts through the ovary and corolla, and becomes erect, bearing the exposed ovules.

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  • Curved ovules are found in Cruciferae, and Caryophyllaceae.

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  • When there are two ovules in the same cell, they may be either collateral, that is, placed side by eh 1 h FIG.

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  • 92), or the one may be erect and the other inverted, as in some species of Spiraea and Aesculus; or they may be placed one above another, each directed similarly, as is the case in ovaries containing a moderate or definite number of ovules.

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  • 91), the ovules, o, are attached to the extended marginal placenta, one above the other, forming usually two parallel rows corresponding to each margin of the carpel.

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  • When the ovules are definite (i.e.

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  • When the ovules are very numerous (indefinite), while at the same time the placenta is not much developed, their position exhibits great variation, some being directed upwards, others downwards, others transversely; and their form is altered by pressure into various polyhedral shapes.

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  • In such cases it frequently happens that some of the ovules are arrested in their development and become abortive.

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  • The female inflorescences vary considerably in organization; in some species the axis of the spike bears solitary ovules, each accompanied by a few bracts, while in others the lateral appendages are catkins, each containing from two to several ovules.

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  • In Bennettites the ovules are left exposed at the apex, but they are by no means so distinctly gymnospermous as.

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  • We have a combination in the same flower of stalked ovules, the structure of which has already been described, and interseminal scales constituting a complex gynoecium, which exhibits in certain features an approach to the angiospermous type, and differs in structure from other Gymnosperm flowers, associated with male organs constructed on a plan almost identical with that.

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  • One large specimen is figured by Heer from Lower Cretaceous rocks of Greenland, and by the side of the frond is shown a carpel with lateral ovules, as in the female flower of Cycas; but an examination of the type-specimen in the Copenhagen Museum led the present writer to regard this supposed carpel as valueless.

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  • empiric self-treatment is more cost-effective and preferable to patients than cyclical monthly prophylactic use of 500 mg clotrimazole vaginal ovules.

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  • The pollen grains grow down from the stigma to fertilize the ovules in the ovary at the base of the style.

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  • Each carpel contains two ovules (female reproductive cells or eggs ), which will grow into seeds.

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  • It may contain one or more ovules, in one or more parts.

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  • The ovary has many cavities with a large number of ovules attached to its walls, and is surmounted by a flat stigma of many radiating rows as in a poppy.

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  • The spores, as in the heterosporous Pteridophyta, are of two kindsmicrospores (pollen grains) borne in microsporangia (pollen sacs) on special leaves (sporophylls) known as stamens, and macrospores (embryo-sac) borne in macrosporangia (ovules) on sporophylls known as carpels.

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  • In GY~~1NospERMsso-called because the ovules (and seeds) are borne on an open sporophyll or carpelthe microsporophylls and macrosporophylls are not as a rule associated in the same shoot and are generally arranged in cone-like structures; one or two small prothallial cells are formed in the germination of the microspore; the male cells are in some older members of the group motile though usually passive.

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  • The ANGIOSFERMS, which are much the larger class, derive their name from the fact that the carpel or carpels form a closed chamber, the ovary, in which the ovules are developedassociated with this is the development of a receptive or stigmatic surface on which the pollen grain is deposited.

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  • described, but with the ovules on the walls of the cavity (not in its axis or centre), a six-parted perianth, a stamen or stamens and stigmas.

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  • The pistil consists of a single carpel with its ovary, style, stigma and solitary ovule or twin ovules.

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  • The ovary is superior and one-celled, with three parietal placentas and numerous ovules; it bears a single style, which ends in a dilated or hood-like stigma (fig.

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  • Vertical section to show the ovules o, attached to the parietes.

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  • Two rows of ovules are seen, one in front and the other in profile.

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  • p, placenta; o, ovules; s, suture, or median line of carpel.

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  • 5), the perianth which is generally petaloid occupying the two outer whorls, followed by two whorls of stamens, with a superior ovary of three carpels in the centre of the flower; the ovary is generally three-chambered and contains an indefinite number of anatropous ovules on axile placentas (see fig.

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  • The ovary is generally two-chambered, with two inverted ovules standing side by side at the inner angle of each chamber.

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  • From the centre, processes (s) go to circumference(t), ending in curved placentaries bearing the ovules.

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  • Both bear their round or ovoid male catkins at the ends of the slender terminal branchlets; the ovoid cones, either terminal or on short lateral twigs, have thick woody scales dilated at the extremity, with a broad disk depressed in the centre and usually furnished with a short spine; at the base of the scales are from three to seven ovules, which become reversed or partially so by compression, ripening into small angular seed with a narrow wing-like expansion.

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  • There are five, or sometimes fewer, carpels, which unite to form an ovary with as many chambers, in each of which are one or two, rarely more, pendulous anatropous ovules, attached to the central column in such a way that the micropyle points outwards and the raphe is turned towards the placenta.

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  • In the simplest instances the pollen of one flower fertilizes the ovules of another on the same plant, owing to the stamens arriving at maturity in any one flower earlier or later than the pistils.

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  • The conidia are fragrant and are carried by bees to the stigma of the bilberry; here they germinate with the pollen and the hyphae pass with the pollen tubes down the style; the former infect the ovules and produce sclerotia, therein reducing the fruits to a mummified condition.

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  • The ovary is incompletely divided into many chambers by the ingrowth of the placentas which bear numerous ovules and form in the fruit a many-seeded short capsule opening by small valves below the upper edge.

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  • The carpel, or aggregate of carpels forming the pistil or gynaeceum, comprises an ovary containing one or more ovules and a receptive surface or stigma; the stigma is sometimes carried up on a style.

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  • The ovary contains one or more ovules borne on a placenta, which is generally some part of the ovary-wall.

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  • In Gymnosperms we have seeds, and the carpels may become modified and close around these, as in Pinus, during the process of ripening to form an imitation of a box-like fruit which subsequently opening allows the seeds to escape; but there is never in them the closed ovary investing from the outset the ovules, and ultimately forming the ground-work of the fruit.

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  • The eight series of Monochlamydeae, containing 36 orders, form groups characterized mainly by differences in the ovary and ovules, and are now recognized as of unequal value.

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  • The petaloid perianth consists of two series, each with three members, which are joined below into a longer or shorter tube, followed by one whorl of three stamens; the inferior ovary is three-celled and contains numerous ovules on an axile placenta; the style is branched and the branches are often petaloid.

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  • The superior ovary - half-inferior in Samolus - bears a simple style ending in a capitate entire stigma, and contains a free-central placenta bearing generally a large number of ovules, which are exceptional in the group Gamopetalae in having two integuments.

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  • The order is divided into five tribes by characters based on differences in position of the ovules - which are generally semianatropous so that the seed is peltate with the hilum in the centre on one side (or ventral), but sometimes, as in Hottonia and (From Strasburger's Lehrbuch der Botanik.) FIG.

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  • The numerous male catkins are generally arranged in dense whorls around the bases of the young shoots; the anther-scales, surmounted by a crest-like appendage, shed their abundant pollen by longitudinal slits; the two ovules at the base of the inner side of each fertile cone-scale develop into a pair of winged seeds, which drop from the opening scales when mature - as in the allied genera.

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  • The same characters will distinguish grasses from the other glumiferous orders, Restiaceae, and Eriocaulonaceae, which are besides further removed by their capsular fruit and pendulous ovules.

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  • yvµvos, naked, nrEp,ua, seed) implies, one characteristic of this group is the absence of an ovary or closed chamber containing the ovules.

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  • Ovules naked, rarely without carpellary leaves, usually borne on carpophylls, which assume various forms. The single megaspore enclosed in the nucellus is filled with tissue (prothallus) before fertilization, and contains two or more archegonia, consisting usually of a large egg-cell and a small neck, rarely of an egg-cell only and no neck (Gnetum and Welwitschia).

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  • From the lower part of a carpel are produced several laterally placed ovules, which become bright red or orange on ripening; the bright fleshy seeds, which in some species are as large as a goose's egg, and the tawny spreading carpels produce a pleasing combination of colour in the midst of the long dark-green fronds, which curve gracefully upwards and outwards from the summit of the columnar stem.

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  • I) on the branched or unbranched stem; (b) the growth of the main stem through the female flower; (c) the presence of a prominent single vein in the linear pinnae; (d) the structure of the female flower, which is peculiar in not having the form of a cone, but consists of numerous independent carpels, each of which bears two or more lateral ovules.

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  • - Characterized by the woolly scaleleaves and carpels; the latter terminate in a thick laminar expansion of triangular form, bearing two placental cushions, on which the ovules are situated.

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  • In Cycas revoluta and C. circinalis each leaf-like carpel may produce several laterally attached ovules, but in C. Normanbyana the carpel is shorter and the ovules are reduced to two; this latter type brings us nearer to the carpels of Dioon, in which the flower has the form of a cone, and the distal end of the carpels is longer and more leaf-like than in the other genera of the Zamieae, which are characterized by shorter carpels with thick peltate heads bearing two ovules on the morphologically lower surface.

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  • Pollination in cycads has always been described as anemophilous, but according to recent observations by Pearson on South African species it seems probable that, at least in some cases, the pollen is conveyed to the ovules by animal agency.

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  • It is often stated that fertilization occurs after the ovules have fallen, but it has been demonstrated by Hirase that this occurs while the ovules are still attached to the tree.

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  • The morphology of the female flowers has been variously interpreted by botanists; the peduncle bearing the ovules has been described as homologous with the petiole of a foliage-leaf and as a shoot-structure, the collar-like envelope at the base of the ovules being referred to as a second integument or arillus, or as the representative of a carpel.

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  • The facts on which this description is based are derived partly from anatomical evidence, and in part from an account given by a Japanese botanist, Fujii, of several abnormal female flowers; in some cases the collar at the base of an ovule, often described as an arillus, is found to pass gradually into the lamina of a leaf bearing marginal ovules (fig.

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  • The occurrence of more than two ovules on one peduncle is by no means rare; a particularly striking example is described by Fujii, in which an unusually thick peduncle bearing several stalked ovules terminates in a scaly bud (fig.

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  • The frequent occurrence of more than two pollen-sacs and the equally common occurrence of additional ovules have been regarded by some authors as evidence in favour of the view that ancestral types normally possessed a greater number of these organs than are usually found in the recent species.

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  • Finally in the yew, as a type of the family Taxeae, the ovules occur singly at the apex of a lateral branch, enclosed when ripe by a conspicuous red or yellow fleshy arillus, which serves as an attraction to animals, and thus aids in the dispersal of the seeds.

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  • Robert Brown was the first to give a clear description of the morphology of the Abietineous cone in which carpels bear naked ovules; he recognized gymnospermy as an important distinguishing feature in conifers as well as in cycads.

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  • 15, D) Sequoia, &c., there are always two sets of bundles; the upper set, having the phloem uppermost, as in the seminiferous scale of Abies or Pinus, are regarded as belonging to the outgrowth from the carpellary scale and specially developed to supply the ovules.

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  • An interesting case has been figured by Masters, in which scales of a cone of Cupressus Lawsoniana bear ovules on the upper surface and stamens on the lower face.

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  • In 1906 he gave an account of the early stages of development of the male and female organs and, among other interesting statements in regard to the general biology of Welwitschia, he expressed the opinion that, as Hooker suspected, the ovules are pollinated by insect-agency.

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  • The scales of the upper or middle series each bear one or two erect ovules.

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  • The flowers spring from, or are enclosed in, a spathe, and are unisexual and regular, with generally a calyx and corolla, each of three members; the stamens are in whorls of three, the inner whorls are often barren; the two to fifteen carpels form an inferior ovary containing generally numerous ovules on often large, produced, parietal placentas.

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  • 26, o), which is the lower portion enclosing the ovules destined to become seeds, and the stigma (g), a portion of loose cellular tissue, the receptive surface on which the pollen is deposited, which is either sessile on the apex of the ovary, as in the poppy, or is separated from it by a prolonged portion called the style (s) .

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  • - The pistil of Tobacco (Nicotiana Tabacum), consisting of the ovary o, containing ovules, the style s, and the capitate stigma g.

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  • - Diagrammatic section of a symmetrical pentamerous flower of Stone-crop (Sedum), consisting of five sepals (s), five petals (p) alternating with the sepals, ten stamens (a) in two rows, and five carpels (c) containing ovules.

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  • It consists essentially of two parts, a basal portion forming a chamber, the ovary, containing the ovules attached to a part called the placenta, and an upper receptive portion, the stigma, which is either seated on the ovary (sessile), as in the tulip and poppy, or is elevated on a stalk called the style, interposed between the ovary and stigma.

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  • Each carpel has its own ovary, style (when present), and stigma, and may be regarded as formed by a folded leaf, the upper surface of which is turned inwards towards the axis, and the lower outwards, while from its margins are developed one or more ovules.

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  • In Cycas the carpels are ordinary leaves, with ovules upon their margin.

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  • The ovules are attached to the placenta, which consists of a mass of cellular tissue, through which the nourishing vessels pass to the ovule.

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  • 1 ovules, developing to form Y (g 9), the fruit.

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  • s, Septum; o, ovules, which form a double row in the inner angle of each chamber.

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  • The ovules (o) are attached to a central placenta, formed by the union of the five ventral sutures.

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  • - Diagrammatic section of a five-carpellary ovary, in which the edges of the carpels, bearing the placentas and ovules o, are not folded inwards.

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  • The placentas are parietal, and the ovules appear sessile on the walls of the ovary.

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  • 92, 93), and the ovules appear in the central angle of the loculi.

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  • - Diagrammatic section of a five-carpellary ovary, in which the septa (s) proceed inwards for a certain length, bearing the placentas and ovules (o).

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  • I, Vertical; 2, horizontal section; c, calyx; d, wall of ovary; o, ovules; p, placenta; s, stigma.

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  • From the centre, processes go to circumference, ending in curved placentas bearing the ovules.

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  • The ovules (o) are attached to a free central placenta, which has no connexion with the walls of the ovary.

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  • In Caryophyllaceae, however, while the placenta is free in the centre, there are often traces found at the base of the ovary of the remains of septa, as if rupture had taken place, and, in rare instances, ovules are found on the margins of the carpels.

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  • But in Primulaceae no vestiges of septa or marginal ovules can be perceived at any period of growth; the placenta is always free, and rises in the centre of the ovary.

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  • o, Ovary; p, free central placenta; g, ovules; s, styles.

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  • - The same cut horizontally, and the halves separated so as to show the interior of the cavity of the ovary o, with the free central placenta p, covered with ovules g.

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  • carpellary leaves, and that in the progress of development these leaves separated from them, leaving the placentas and ovules free in the centre; or by supposing that the placentas are not marginal but axile formations, produced by an elongation of the axis, and the carpels verticillate leaves, united together around the axis.

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  • Ovules are most usually produced on the margins of FIG.

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  • The carpellary leaves are sometimes united in such a way as to leave an opening at the apex of the pistil, so that the ovules are exposed, as in mignonette.

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  • In Leontice thalictroides (Blue Cohosh), species of Ophiopogon, Peliosanthes and Stateria, the ovary ruptures immediately after flowering, and the ovules are exposed; and in species of Cuphea the placenta ultimately bursts through the ovary and corolla, and becomes erect, bearing the exposed ovules.

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  • Curved ovules are found in Cruciferae, and Caryophyllaceae.

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  • When there are two ovules in the same cell, they may be either collateral, that is, placed side by eh 1 h FIG.

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  • 92), or the one may be erect and the other inverted, as in some species of Spiraea and Aesculus; or they may be placed one above another, each directed similarly, as is the case in ovaries containing a moderate or definite number of ovules.

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  • 91), the ovules, o, are attached to the extended marginal placenta, one above the other, forming usually two parallel rows corresponding to each margin of the carpel.

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  • When the ovules are definite (i.e.

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  • When the ovules are very numerous (indefinite), while at the same time the placenta is not much developed, their position exhibits great variation, some being directed upwards, others downwards, others transversely; and their form is altered by pressure into various polyhedral shapes.

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  • In such cases it frequently happens that some of the ovules are arrested in their development and become abortive.

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  • The female inflorescences vary considerably in organization; in some species the axis of the spike bears solitary ovules, each accompanied by a few bracts, while in others the lateral appendages are catkins, each containing from two to several ovules.

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  • In the upper part of the nucellus is a cavity or pollen-chamber, with a narrow canal leading into it, precisely as in the ovules of Stangeria or other Cycads at the present day (fig.

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  • In Bennettites the ovules are left exposed at the apex, but they are by no means so distinctly gymnospermous as.

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  • which possess fully developed male organs consisting of sporangia with spores (pollen-grains), surrounding a conical central receptacle bearing numerous small and probably functionless or immature ovules (fig.

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  • We have a combination in the same flower of stalked ovules, the structure of which has already been described, and interseminal scales constituting a complex gynoecium, which exhibits in certain features an approach to the angiospermous type, and differs in structure from other Gymnosperm flowers, associated with male organs constructed on a plan almost identical with that.

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  • Fossil flowers of a type more like that of modern Cycads are few in number, and it is not by any means certain that all of those described as Cycadean flowers and seeds were borne by plants which should be included in the Cycadophyta; a few female flowers have been described from Rhaetic rocks of Scania and elsewhere under the name Zamiostrobus - these consist of an axis with slender pedicels or carpophylls given off at a wide angle and bearing two ovules at the distal end; the structure is in fact similar to that of a Zamia female flower, in which the internodes of the peduncle have been elongated so as to give a looser arrangement to the carpels.

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  • One large specimen is figured by Heer from Lower Cretaceous rocks of Greenland, and by the side of the frond is shown a carpel with lateral ovules, as in the female flower of Cycas; but an examination of the type-specimen in the Copenhagen Museum led the present writer to regard this supposed carpel as valueless.

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  • The ovary has many cavities with a large number of ovules attached to its walls, and is surmounted by a flat stigma of many radiating rows as in a poppy.

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  • The ANGIOSFERMS, which are much the larger class, derive their name from the fact that the carpel or carpels form a closed chamber, the ovary, in which the ovules are developedassociated with this is the development of a receptive or stigmatic surface on which the pollen grain is deposited.

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  • described, but with the ovules on the walls of the cavity (not in its axis or centre), a six-parted perianth, a stamen or stamens and stigmas.

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  • The pistil, which is above the rest of the members of the flower, consists of two carpels joined at their edges to form the ovary, which becomes two-celled by subsequent ingrowth of a septum from these united edges; a row of ovules springs from each edge.

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  • But in Primulaceae no vestiges of septa or marginal ovules can be perceived at any period of growth; the placenta is always free, and rises in the centre of the ovary.

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  • The pistil, which is above the rest of the members of the flower, consists of two carpels joined at their edges to form the ovary, which becomes two-celled by subsequent ingrowth of a septum from these united edges; a row of ovules springs from each edge.

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