A CONTRIBUTION TO THE EMBRYOLOGY OF CYPERUS ROTUNDUS L., SCIRPUS MUCRINATUS L., AND KYLLINGA MELANOSPORA NEES.

1965 ◽  
Vol 43 (12) ◽  
pp. 1539-1547 ◽  
Author(s):  
Pushpa Khanna
Keyword(s):  
Embryo Sac ◽  
Middle Layer ◽  
Cell Plate ◽  
Cyperus Rotundus ◽  
Cleavage Furrow ◽  
Double Fertilization ◽  
Polygonum Type ◽  
Cell Embryo ◽  
A Cell ◽  
Mother Cells

The anther is tetralocular and its wall consists of four layers: epidermis, endothecium, a middle layer, and the uninucleate tapetum. The endothecial cells develop characteristic fibrous thickenings. Microspore mother cells divide meiotically to form four nuclei. One of them grows in size and becomes the functional nucleus of the pollen grain while the three non-functional ones are pushed to the periphery. A cleavage furrow accompanied by a cell plate separates them from the functional nucleus. Similar walls, though less prominent, separate the non-functional nuclei from each other. The walls are comparatively distinct in Cyperus rotundus and Kyllinga melanospora.The ovule is anatropous, bitegmic, and crassinucellate. The inner integument forms the micropyle. An outgrowth from the funiculus gives rise to an obturator. The hypodermal archesporial cell divides to form a two-layered parietal tissue and a sporogenous cell. Embryo sac is of the Polygonum type. Double fertilization takes place.The embryogeny conforms to the Juncus variation of the onagrad type in Cyperus rotundus and Kyllinga melanospora and to the asterad type in Scirpus mucrinatus.The integuments each are two-layered. The inner becomes three- to four-layered at the micropylar end. Both of them ultimately fuse to form a thin testa. The thick pericarp also functions as testa.

The floral morphology and embryology of Themeda australis (R. Br.) Stapf

1964 ◽  
Vol 12 (2) ◽  
pp. 157 ◽  
Author(s):  
PS Woodland
Keyword(s):  
Embryo Sac ◽  
Pollen Grains ◽  
Low Fertility ◽  
Linear Tetrad ◽  
Polygonum Type ◽  
Morphological Variations ◽  
Endosperm Formation ◽  
Secretory Type ◽  
Successive Cytokinesis ◽  
Mother Cells

A comparative study was carried out between diploid and tetraploid races of Themeda australis from Armidale and Cobar, respectively. Some morphological variations occur in both populations, but sporogenesis and gametogenesis are identical. The anther is tetrasporangiate and the development of its four-layered wall is described. The tapetum is of the secretory type and its cells become binucleate at the initiation of meiosis in the adjacent microspore mother cells which undergo successive cytokinesis. Microspore tetrads are usually isobilateral and the pollen grains are three-celled at dehiscence, which takes place by lateral longitudinal slits. The ovule is of a modified anatropous form and bitegmic, the broad micropyle being formed of both integuments. The single hypodermal archesporial cell develops directly into the megaspore mother cell and the nucellar epidermis undergoes periclinal and anticlinal divisions to form a conspicuous epistase. The chalaza1 megaspore of the linear tetrad gives rise to a Polygonum-type embryo sac. Material from the Armidale population showed one embryo sac per ovule, but two to five embryo sacs were present in that from Cobar. Embryogeny is typically graminaceous and endosperm formation is at first free-nuclear, later becoming cellular. Polyembryony follows fertilization of several embryo sacs within the same ovule. The reasons for low fertility of T. australis and poor germination of seeds are discussed.

Floral Morphology of the family compositae, III. Embryology of Siegesbeckia orientalis L

1965 ◽  
Vol 13 (1) ◽  
pp. 1 ◽  
Author(s):  
S Misra
Keyword(s):  
Vascular Bundle ◽  
Floral Morphology ◽  
Embryo Sac ◽  
Cell Plate ◽  
Pollen Grain ◽  
Polygonum Type ◽  
Outermost Layer ◽  
The Family ◽  
Siegesbeckia Orientalis ◽  
Ray Florets

The capitulum is heterogamous and globose with a biseriate involucre, the outer most bracts being radiating and glandular wuhile the inner are boat-shaped, enclosing the ray florets. The disc florets are also subtended by bracts, although one or two central bracts do not bear florets. The corolla of the ray florets is bilabiate in material collected from Mussoorie, India, while posterior lip is suppressed in that form Mt.Abu. The stamen and the style correspond to types 2 and V11 respectively of Small (1919). Occasional staminodes in the ray florets represent a reversionary feature. The development and structure of the microsporangium is described. An ephemeral cell plate is formed after meiosis 1 of the sporocytes. The mature pollen grain is tricellular; the male garnets are elongated and laxly spiral. The ovule develops slightly to one side of the base of the loculus, and a funicular vascular bundle branches in the integument. The endothelium is uniseriate, later becoming multiseriate at the two ends of the embryo sac, and it develops a cuticle on its inner face which persists in the seed after the endothelium degenerates. The development of the embryo sac is of the Polygonum type. The antipodals and one synergid become haustorial after fertilization. Supernumery pollen tubes were noted. Failure of fertilization in exceptional cases results in unusaul behaviour of the endothelium, degeneration of the embryo sacs, and seed sterility. The endosperm is nuclear, later becoming cellular, and is outermost layer persists in the seed. Embryogeny is of the asterad type.

Sporogenesis, Gametogenesis, and embryogeny of Wahlenbergia bicolor N. Lothian

1963 ◽  
Vol 11 (2) ◽  
pp. 152 ◽  
Author(s):  
G Want
Keyword(s):  
Mother Cell ◽  
Embryo Sac ◽  
Pollen Grains ◽  
Type A ◽  
Middle Layer ◽  
Anther Wall ◽  
Suspected Case ◽  
Polygonum Type ◽  
Chalazal Megaspore ◽  
Coastal Species

In Wahlenbergia bicolor, the anther wall is composed of four layers: epidermis, endothecium, middle layer, and tapetum. Wall formation and microsporogenesis are described, and the pollen grains are shed at the two-celled condition. The ovules are tenuinucellate, with a hypodermal archesporial cell which develops directly as the megaspore mother cell. Megasporogenesis is normal, and a monosporic eight-nucleate embryo sac of the most common Polygonum type develops from the chalazal megaspore. The antipodals degenerate before fertilization. The development of the embryo is of the solanad type. A suspected case of polyembryony was observed. The endosperm is cellular from its inception, and so conforms to the Codonopsis type. A micropylar and a chalazal haustoriurn, both consisting of two uninucleate cells, are formed from the endosperm. Comparative studies were made with a known but as yet undescribed coastal species of Wahlenbergia, and no differences were found.

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.

Studies on the Monimiaceae. III. Gametophyte development of Laurelia novae-zelandiae A. Cunn. (subfamily Atherospermoideae)

1969 ◽  
Vol 17 (3) ◽  
pp. 425 ◽  
Author(s):  
FB Sampson
Keyword(s):  
Generative Cell ◽  
Embryo Sac ◽  
Radial Wall ◽  
Tetrad Stage ◽  
Polygonum Type ◽  
Gametophyte Development ◽  
Pollen Mother Cells ◽  
Secretory Type ◽  
Mother Cells ◽  
Unusual Type

Floral ontogeny and gametophyte development of the New Zealand endemic species Laurelia novae-zelandiae is described. The microsporangium has three to five wall layers inside the epidermis, including a typically thickened endothecium and a tapetum of the secretory type in which the cells become binucleate during the first meiotic division of pollen mother cells. Cytokinesis of pollen mother cells is of an unusual type in which centrifugal cell plates do not develop until the end of meiosis 11. The generative cell of the pollen grain is cut off against what represents a radial wall of the grain with reference to the tetrad stage. Pollen is two- or three-celled when shed. Ovules are bitegmic, crassinucellate, and anatropous with a Polygonum type of embryo sac development.

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.

The embryology of Kunzea capitata Reichb

1969 ◽  
Vol 17 (1) ◽  
pp. 97 ◽  
Author(s):  
N Prakash
Keyword(s):  
Outer Integument ◽  
Cell Formation ◽  
Embryo Sac ◽  
Pollen Grains ◽  
Basic Type ◽  
Ring Stage ◽  
Polygonum Type ◽  
Signet Ring ◽  
Mother Cells ◽  
Antipodal Cells

The anther is tetrasporangiate and the development of its wall is of the Basic type. Ubisch granules are formed on the surface of the tapetum at the signet-ring stage of the pollen grains. The anther dehisces by longitudinal slits, and pollen grains are shed at the two-celled stage. The female archesporium is subepidermal and cuts off the primary parietal cell. A six-layered parietal tissue is formed below the nucellar epidermis by the time megasporogenesis is completed. The flowers are protandrous, and in any given bud meiosis in megaspore mother cells follows that in microspore mother cells. Embryo sac development is of the Polygonum type and the antipodal cells are ephemeral. Cell formation in the nuclear endosperm commences at the micropylar end and proceeds towards the chalaza. Embryogeny corresponds to the Onagrad type and no evidence of polyembryony was found. Both the integuments take part in the formation of the seed coat, in which the cells of the outer layer of the outer integument are conspicuously elongated. A comparison is made with the embryological findings in other myrtaceous plants.

A contribution to the life history of Angophora floribunda (Sm.) Sweet (Myrtaceae)

1969 ◽  
Vol 17 (3) ◽  
pp. 457 ◽  
Author(s):  
N Prakash
Keyword(s):  
Floral Development ◽  
Outer Integument ◽  
Embryo Sac ◽  
Pollen Grains ◽  
Flower Buds ◽  
Polygonum Type ◽  
Mature Embryos ◽  
History Of ◽  
Sterile Pollen ◽  
Mother Cells

The flower buds of Angophora floribunda appear in the last week of November and anthesis occurs in the middle of January the following year. There is no prolonged resting phase at any stage during embryology and the seeds are shed during late February to early March. In floral development, the petals are the last structures to be formed. Early anther development precedes corresponding stages in the ovules of the same flower, but events in the ovules proceed more rapidly and meiosis occurs simultaneously in the spore mother cells of both organs. The mature two-celled pollen grains are shed when the ovules contain four-or eight-nucleate embryo sacs. Many flowers bear anthers containing only sterile pollen grains, which occur either singly or as tetrads. Various abnormalities in the development of the pollen are reported, and the anthers containing sterile pollen neither develop fibrous bands in the endothecium nor do they dehisce. The ovules are bitegminal, crassinucellar, and hemianatropous. Occasional bifurcation of the inner integument was observed and a hypostase differentiates at the four-nucleate stage of the embryo sac. The embryo sac follows the Polygonum type of development and is five-nucleate and four-celled when mature. The endosperm is Nuclear in origin, and in about half the seeds examined a granular unidentified substance accumulates in the embryo sac. The development of the embryo is irregular and the seedlings bear a collar-like structure at the junction of the hypocotyl and the radicle. The mature embryos are usually dicotyledonous but rarely tricotyledonous. The seed coat is formed exclusively by the outer integument; in the ripe seed it consists of an outer epidermis of large, palisade-like, thin-walled, tanniniferous cells and an inner crystalliferous layer.

A morphological and embryological study of Callicoma serratifolia Andr. (Cunoniaceae).

1981 ◽  
Vol 29 (6) ◽  
pp. 721 ◽  
Author(s):  
MJ Kennedy ◽  
N Prakash
Keyword(s):  
New England ◽  
Embryo Sac ◽  
Leaf Size ◽  
Leaf Margin ◽  
Polygonum Type ◽  
Group A ◽  
Morphological Differences ◽  
Perforation Plates ◽  
Group B ◽  
Mother Cells

The morphological and anatomical features of Callicoma serratifolia populations on the New England Tablelands reveal the existence of two distinct groups, here designated A and B. Major morphological differences between these groups include leaf margin serration, distribution of hairs on stems and branches, possession of one trichome type in group A in contrast to two types found in group B, overall leaf size and venation patterns. At the anatomical level the differences are in vessel dimensions and the number of bars on perforation plates. Features common to both groups include bisexual, pentamerous and apetalous flowers, tetrasporangiate versatile anthers with a glandular tapetum, simultaneous cytokinesis in pollen mother cells and colporate pollen which is released at the 2-celled stage. The ovules are anatropous, bitegmic and crassinucellate with a polygonum type of embryo sac development. The endosperm is of the nuclear type. Both integuments contribute to the formation of the seed coat. The embryo is straight. While in its vegetative anatomy C. serratifolia resembles members of the families Eucryphiaceae, Saxifragaceae and Escalloniaceae, embryologically it closely resembles Baueraceae and less closely the subfamily Hydrangeoideae of the Saxifragaceae.

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.

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