Gametogenesis and seed development in Hereroa hesperantha (Dtr.) Dtr. et Schwant (Aizoaceae).

1967 ◽  
Vol 15 (3) ◽  
pp. 425 ◽  
Author(s):  
N Prakash
Keyword(s):  
Female Gametophyte ◽  
Mature Seed ◽  
Anther Wall ◽  
Polygonum Type ◽  
Multinucleate Cells ◽  
Cell Functions ◽  
Innermost Layer ◽  
Tapetal Cells ◽  
Sporadic Cases ◽  
Mother Cells

Hereroa hesperantha belongs to the embryologically little known group of mesembryanthemums. The anther wall is four-layered, the innermost layer constituting the secretory tapetum with multinucleate cells. Prominent Ubisch granules dot the inner tangential and radial walls of the tapetal cells. Cytokinesis in the microspore mother cells is simultaneous, and either tetrahedral or decussate tetrads are formed. The mature pollen is three-celled. The ovules are anacampylotropous, bitegminal, crassinucellar, and non-arillate. The need for employing a uniform terminology for ovular curvature in the Aizoaceae is stressed in view of the existing confusion. The ovules are borne on parietal placentae each of which bears an obturator. The archesporium is one- to many-celled, but only one cell functions. Sporadic cases of double megaspore tetrads and two-nucleate dyad cells were observed. The development of the female gametophyte conforms to the Polygonum type. The synergids and antipedal cells are short-lived. The endosperm is of the Nuclear type and produces a weakly haustorial chalazal caecum. Perisperm takes over the function of endosperm in the mature seed. The embryogeny corresponds to the Solanad type. There is a massive suspensor with some multinucleate cells. The mature seed coat resembles closely that of the Cactaceae and comprises the outer layer of the outer and inner layer of the inner integument, both of which become greatly enlarged and tanniniferous. In features like the presence of staminodes and inferior ovary and the absence of aril, Hereroa differs from other Aizoaceae.

Floral morphology and embryology of two Australian species of Citrus (Rutaceae)

2001 ◽  
Vol 49 (2) ◽  
pp. 199 ◽  
Author(s):  
Kerri Clarke ◽  
Nallamilli Prakash
Keyword(s):  
Female Gametophyte ◽  
Floral Morphology ◽  
Anther Wall ◽  
Microspore Development ◽  
Common Occurrence ◽  
Citrus Species ◽  
Polygonum Type ◽  
Australian Species ◽  
Tapetal Cells ◽  
Antipodal Cells

The floral morphology and embryology of two species of Australian Citrus L. occurring in the most southerly range of the genus, C. australasica F.Muell. and C. australis (Mudie) Planchon, have been studied. Cytokinesis in the microsporocytes was simultaneous resulting in tetrahedral tetrads. Tapetal cells were bi- to multinucleate and unevenly one- or two-layered. Microspore development was frequently asynchronous. Anther wall consisted of a layer of endothecium, three to five middle layers and one or two layers of Secretory tapetum. The ovules were anatropous, bitegmic and crassinucellate. Although multiple sporogenous cells that grew into multiple megasporocytes were common, occurrence of twin or multiple gametophytes was rare. Development of the female gametophyte was of the Polygonum type, with antipodal cells frequently persisting until after fertilisation. Endosperm was of the Nuclear type while embryogeny was of the Onagrad type. Both integuments contributed to the seed coat. Cells of the outer layer of the testa developed fibrous thickenings and secreted mucilage. Seeds were monoembryonate and seed germination was hypogeal. The recent move incorporating Australian native citrus species in to the genus Citrus was supported on the grounds of close embryological similarities.

Floral morphology, embryology, and relationships of the Berberidaceae.

1969 ◽  
Vol 17 (1) ◽  
pp. 69 ◽  
Author(s):  
RLN Sastri
Keyword(s):  
Floral Morphology ◽  
Embryo Sac ◽  
Pollen Grains ◽  
Wall Layer ◽  
Vascular Supply ◽  
Anther Wall ◽  
Polygonum Type ◽  
Innermost Layer ◽  
Secretory Type ◽  
Mother Cells

The floral morphology and development of the gametophytes in Berberis umbellata and Mahonia leschenaultii have been studied. All the perianth members have three traces each in B. umbellata while in M. leschenaultii the members of the outer three whorls have five veins each and those of the fourth three veins each. The vascular supply for the inner two whorls of perianth and the stamens arises as conjoint traces. The wall of the gynoecium is traversed by numerous bundles with some concentrated in the placental region. The dorsal and ventral bundles are differentiated in M. leschenaultii but not in B. umbellata. The tricarpellary interpretation of the gynoecium is shown to be unconvincing. The gynoecium is regarded as monocarpellary. The mature anther wall is five-layered including the epidermis, of which the innermost layer forms the tapetum of secretory type. The tapetal cells are four to eight-nucleate. The hypodermal wall layer develops into a fibrous endothecium in M. leschenaultii. In B. urnbellata, the endothecium develops U-shaped thickenings. Division of pollen mother cells is successive. Pollen tetrads are usually isobilateral. Mature pollen grains are three-colpate and two-celled. The ovule is anatropous, bitegmic, and crassinucellate. In B. umbellata, a rudimentary aril is formed as an outgrowth of the funiculus. The single hypodermal archesporial cell in the young ovule cuts off a parietal cell. Development of the embryo sac is of the Polygonum type. The synergids show filiform apparatus and are persistent. The antipodals are large and persistent in M. leschenaultii and ephemeral in B. umbellata. The relationships of the Berberidaceae (sensu Hutchinson 1959) to the Menispermaceae, Lardizabalaceae, and the Ranunculaceae (sensu lato) are discussed.

Embryology of the dioecious Australian endemic Lomandra longifolia (Lomandraceae)

2008 ◽  
Vol 56 (8) ◽  
pp. 651 ◽  
Author(s):  
Nabil M. Ahmad ◽  
Peter M. Martin ◽  
John M. Vella
Keyword(s):  
Middle Layer ◽  
Endosperm Development ◽  
Anther Wall ◽  
Polygonum Type ◽  
Cell Functions ◽  
Mature Ovule ◽  
Cell Layers ◽  
Nucellar Tissue ◽  
Successive Cytokinesis ◽  
Dermal Cells

Microsporogenesis, embryogeny and endosperm development of Lomandra longifolia Labill. are described in detail. The formation of the anther wall is the basic type composed of four cell layers, namely an epidermis, an endothecium, one middle layer and a tapetum. The tapetum layer has glandular, uninucleate cells. Successive cytokinesis follows meiosis, subsequently forming a tetrahedral tetrad of microspores. The ovule in each carpel is hemitropous, crassinucellate and bitegmic, with the micropyle formed by the inner integument. The archesporial cell divides periclinally to form the primary parietal and primary sporogenous cells. The sporogenous cell functions as the megaspore mother cell, whereas the parietal cell divides to give rise to two parietal layers. The mature megagametophyte, which has enlarged synergids and antipodals, is of the Polygonum type, with the normal complement of seven cells and eight nuclei. Nucellar tissue in the mature ovule consists of enlarged dermal cells and irregular subdermal cells surrounding a central strand of markedly smaller cells. Endosperm development is of the nuclear type. Embryo development is of the Graminad type, characterised by oblique zygotic and early pro-embryonic divisions.

scholarly journals Ovule development, megasporogenesis, and megagametogenesis of Fouquieria fasciculata (Willd. ex Roem. & Schult.) Nash (Fouquieriaceae)

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Fabiola Soto-Trejo ◽  
Sergio Zamudio-Ruiz ◽  
Silvia Espinosa-Matías
Keyword(s):  
Female Gametophyte ◽  
Developmental Patterns ◽  
Polygonum Type ◽  
The Family ◽  
Innermost Layer ◽  
Type Pattern ◽  
Histochemical Tests ◽  
Single Genus ◽  
Study Species ◽  
Eleven Species

Background: Fouquieriaceae is a small family that consists of a single genus, Fouquieria, with eleven species occurring mostly in arid and semiarid regions of Mexico and the southwestern United States. The development of the ovule and the female gametophyte has been poorly characterized in species of the family; thus, it is proposed to carry out a detailed study on the development of the ovule, megasporogenesis and megagametogenesis in Fouquieria fasciculata. Questions: How are the developmental patterns of the ovule and the female gametophyte in Fouquieria fasciculata? Study species: Fouquieria fasciculata (Willd. ex Roem. & Schult.) Nash (Fouquieriaceae). Methods: Embryology, morphology and histochemical tests of floral buds and flowers at pre-anthesis of Fouquieria fasciculata were examined using light microscopy and scanning electron microscopy. Results: The ovules of Fouquieria fasciculata are anatropous, bitegmic and tenuinucellate, and the micropyle is formed by the inner integument. The innermost layer cells of the inner integument form an integumentary tapetum or endothelium. The cells of integumentary tapetum are characterized by very conspicuous wall thickenings on the inner tangential side, and are radially elongated surrounding the nucellus. The pattern of development of the female gametophyte is monosporic Polygonum-type, and the formation of a lateral haustorium was observed. Conclusions: This investigation describes in detail the development of the ovule and the female gametophyte ofFouquieria fasciculata. Our results show interesting features, such as the differentiation of an integumentary tapetum, a monosporic Polygonum-type pattern of development and the formation of lateral haustorial arm in the female gametophyte.

Anther and Ovule Development in Tasmannia (Winteraceae)

1992 ◽  
Vol 40 (6) ◽  
pp. 877 ◽  
Author(s):  
N Prakash ◽  
AL Lim ◽  
FB Sampson
Keyword(s):  
Mother Cell ◽  
Female Gametophyte ◽  
Cell Plate ◽  
Basic Type ◽  
Ovule Development ◽  
Linear Tetrad ◽  
Polygonum Type ◽  
Secretory Type ◽  
Mother Cells ◽  
Female Gametophyte Development

Three species of Tasmannia R.Br. ex DC., T. glaucifolia, T. insipida and T. stipitata are studied. The anther is tetrasporangiate and its waU development conforms to the Basic type. The tapetum follows the secretory type of development. Cytokinesis in the microspore mother cells is simultaneous but an evanescent cell plate is present at telophase I and anaphase I1 during meiosis. Pollen tetrads are permanent and tetrahedral. The mature pollen is anaulcerate, reticulate and 2-celled. The ovule. is anatropous, bitegmic and crassinucellate. The micropyle in T. stipitata and T. Glaucifolia is formed by the inner integument only whereas in T. insipida it is formed by both the integuments and is zigzag in outline. Meiosis in the single megaspore mother cell produces a linear or T-shaped megaspore tetrad in T. stipitata and T. glaucifolia but only a linear tetrad in T. insipida. Female gametophyte development is of the monosporic Polygonum type. Fertilisation is porogamous; triple fusion and syngamy occur simultaneously.

Sexual reproduction in subalpine fir (Abies lasiocarpa)

1981 ◽  
Vol 59 (12) ◽  
pp. 2650-2666 ◽  
Author(s):  
Hardev Singh ◽  
John N. Owens
Keyword(s):  
Female Gametophyte ◽  
Pollen Grains ◽  
Reproductive Phenology ◽  
Abies Lasiocarpa ◽  
Subalpine Fir ◽  
Young Embryo ◽  
Tapetal Cells ◽  
Well Differentiated ◽  
Mother Cells ◽  
Embryonal Mass

Reproductive phenology and anatomy of postdormancy phases of a population of Abies lasiocarpa (Hook.) Nutt. (subalpine fir) from a natural stand near Prince George, B.C., have been studied. The plants exhibited a 1-year type of reproductive cycle. By the end of March, the pollen cones had broken dormancy and contained pollen mother cells (PMC) in premeiotic stages. The PMCs entered meiosis in the 1st week of April and formed tetrads in the 3rd week. The tapetal cells, meanwhile, became binucleate, and then several went through endomitoses. The tapetal cell walls dissolved as the microspores separated from the tetrads. Orbicules were present around the degenerating cytoplasms of tapetal cells. Pollen grains were shed at the five-celled stage in the 3rd week of May.By the end of March, the ovulate cones had also broken dormancy and the ovules contained one to three hypodermal archesporial cells. Initiation of the integument and the formation of megaspore triads were observed in the 3rd week of April. By the 3rd week of May, at the time of pollination, the integument had developed a stigmatic micropylar funnel which received the pollen grains. During the postpollination stages the flange of the funnel became folded, and the nucellus grew up closer to the pollen grains. The nucellar cells at its tip degenerated to form a pollen chamber which contained the pollen grains. Pollen germination, pollen tube growth through the nucellus, and syngamy took only 4–6 days, and occurred at the end of June.The female gametophyte was rather long and narrow and bore two to three archegonia. The proembryo comprised four tiers of four cells each. The first set of suspensors developed from the subterminal tier of cells. The four terminal cells formed the embryonal mass but they contributed unequally. The proximal cells of the embryonal mass formed a massive secondary suspensor. Differentiation of root initials and the initiation of cotyledons in the young embryo took place in the 4th week of July, and the seeds matured in the 3rd week of August. The mature seed comprised a long and well-differentiated embryo, the female gametophyte, most of whose cells were gorged with protein bodies and lipid droplets, and a thick seed coat which was internally differentiated into three tissue layers. The outermost layer of gametophytic cells was devoid of any storage products.

Studies on the Monimiaceae. I. Floral morphology and gametophyte development of Hedycarya arborea J.R. et.G. Forst. (subfamily Monimioideae)

1969 ◽  
Vol 17 (3) ◽  
pp. 403 ◽  
Author(s):  
FB Sampson
Keyword(s):  
Cell Division ◽  
Floral Morphology ◽  
Generative Cell ◽  
Embryo Sac ◽  
Polygonum Type ◽  
Australian Species ◽  
Tapetal Cells ◽  
Pollen Traps ◽  
Secretory Type ◽  
Mother Cells

Inflorescences, flowers, and floral vascularization of the New Zealand endemic species Hedycarya arborea are described. Varying carpel vasculature suggests derivation of the uniovulate condition in Hedycarya from ancestors having multiovulate carpels with ovules in two rows, Floral ontogeny is described and it is noted that the terminal stigmatic region of the carpel develops from a solid terminal meristem, in contrast to many woody Ranales in which the stigma consists of crests surrounding the carpel cleft. The stigmatic surface is a mass of globose projections, apparently serving as pollen traps. No comparable type of stigma has previously been reported in the woody Ranales. The microsporangium has a typically thickened endothecium and a tapetum of the secretory type with tapetal cells becoming binucleate during the first meiotic division of pollen mother cells. Pollen mother cell division is of the successive type with cytokinesis by centrifugally extending cell plates. The generative cell is cut off towards the distal face of the microspore. The pollen, in permanent tetrads, is shed in the two-celled condition. Ovules are bitegmic, crassinucellate, and anatropous with a Polygonum type of embryo sac development. Some comparisons are made with the Australian species Hedycarya angustifolia.

scholarly journals A Contribution to the Embryology of Rhynchelytrum repens (Willd) C.E. Hubbard

1970 ◽  
Vol 7 (7) ◽  
pp. 37-40 ◽  
Author(s):  
Mohammed Inamuddin ◽  
Beatrice Were ◽  
Mohammad Saquib
Keyword(s):  
Mother Cell ◽  
Female Gametophyte ◽  
Pollen Grains ◽  
Middle Layer ◽  
Microspore Mother Cell ◽  
Polygonum Type ◽  
Dense Cytoplasm ◽  
Scientific World ◽  
Tapetal Cells ◽  
Functional Megaspore

The present investigation deals with morphological and embryological studies of Rhynchelytrum repens (Willd) C.E. Hubbard. The development of anther walls are found to be Monocotyledonous type. The tapetal cells are substantially large, glandular and uninucleate. The middle layer is ephemeral and their cells are small in size. It is sandwiched between endothecial and tapetal layer. The endothecial cells are large and develop fibrous thickenings. The microspore mother cell undergoes two successive reduction divisions, giving rise to isobilateral microspore tetrad. The tetrad separates and give rise to four pollen grains. Occasionally, the anther show degenerating pollen grains before dehiscence. Formation of Ubisch's bodies has also been observed. The pollen grains shed at three celled stage. The exine is thick while intine is thin. The ovule is anatropous, bitegmic and crassinucellate. The female archesporial cell becomes large with dense cytoplasm. It directly functions as megaspore mother cell and undergoes two meiotic divisions to produce a linear megaspore tetrad. The micropylar three cells degenerate and chalazal one becomes functional. The chalazal functional megaspore undergoes three mitotic divisions without wall formation and produces 8-nucleate embryosac. Such 8-nucleate embryosac organizes into Polygonum type of embryosac. It is interesting to note that some somatic cells of the ovule undergo nuclear divisions and give rise to facultative apomictic embryosacs. Key Words: Eldoret; Microsporangium; Ubisch's bodies; Facultative apomixis; Female gametophyte. DOI: 10.3126/sw.v7i7.3822 Scientific World Vol.7(7) 2009 pp.37-40

Life history of Tetragonia tetragonioides (Pall.) O. Kuntze

1967 ◽  
Vol 15 (3) ◽  
pp. 413 ◽  
Author(s):  
N Prakash
Keyword(s):  
Cell Formation ◽  
Embryo Sac ◽  
Pollen Grains ◽  
Mature Embryo ◽  
Polygonum Type ◽  
Innermost Layer ◽  
Glandular Cells ◽  
History Of ◽  
Mother Cells ◽  
Tetragonia Tetragonioides

Accessory flowers arise from the surface of inferior ovaries in 25 % of the flowers of Tetragonia, suggesting an axial nature of the inferior ovary. The ovary is six to nine-loculed, with a single pendulous ovule in each locule. The anther is tetrasporangiate. The innermost layer of the four-layered wall constitutes a secretory tapetum with multinucleate cells. Cytokinesis in microspore mother cells is simultaneous and results in tetrahedral or decussate tetrads. The pollen grains are shed at the three-celled stage. The ovules are bitegminal, crassinucellar, and anacampylotropus. The funiculus is long and bears an obturator of glandular cells. The inner integument forms the micropyle and forms a collar at the distal end. A nucellar cap is present. The nucellus persists in the seed as perisperm. The archesporium is multicelled, although only a single cell develops. Following meiosis the megaspore mother cell gives rise to a linear row of three or four megaspores, of which only the chalaza1 functions to form an embryo sac of the Polygonum type. The endosperm is of the Nuclear type and eventually assumes a horseshoe shape. Cell formation is restricted to the micropylar region, the rest remaining nuclear until consumed by the embryo. The embryogeny is of the Solanad type, and the mature embryo is curved and dicotyledonous.

Some aspects of the life history of Callistemon citrinus (Curt.) Skeels

1969 ◽  
Vol 17 (1) ◽  
pp. 107 ◽  
Author(s):  
N Prakash
Keyword(s):  
Life History ◽  
Female Gametophyte ◽  
Embryo Sac ◽  
Basic Type ◽  
Cultivated Plants ◽  
Anther Wall ◽  
Polygonum Type ◽  
Native Populations ◽  
History Of ◽  
Antipodal Cells

Pollen development is irregular in native populations but regular in the cultivated plants investigated. Development of the anther wall is of the Basic type and the tetrasporangiate anthers shed their pollen at the two-celled stage through longitudinal slits. The single vascular bundle of each stamen gives off two traces in the connective. The ovules are anatropous, crassinucellar, and bitegmic. The swollen distal ends of both integuments form the micropyle. The single archesporial cell cuts off a parietal cell, and during megasporogenesis a one- to three-layered parietal tissue is formed which collapses during the development of the embryo sac. Occasionally the megaspore mother cell degenerates but in these instances the growth of the ovule is unimpaired. The female gametophyte follows the Polygonum type of development, and when mature is eight-nucleate and includes three ephemeral antipodal cells. Some abnormalities pertaining to the number and arrangement of nuclei in the embryo sac have been observed and hardly 4% of the ovules form fertile seeds. The seed coat is formed from both the integuments. A hypostase is differentiated in the seed.

Sign in / Sign up

Export Citation Format

Share Document