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.

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.

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.

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 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 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.

scholarly journals Studies on the Morphology, Ontogeny and Embryology of the Flowers of Hedycarya Arborea J.R. et G. Forst. (Subfamily Monimioideae) and Laurelia Novae-Zelandiae A. Cunn. (Subfamily Atherospermoideae) of the Family Monimiaceae

2021 ◽  
Author(s):  
◽  
Frederick Bruce Sampson
Keyword(s):  
Generative Cell ◽  
Embryo Sac ◽  
Pollen Grains ◽  
Tetrad Stage ◽  
Pollen Mother Cells ◽  
The Family ◽  
Long Time ◽  
External Part ◽  
Mother Cells ◽  
And Function

<p>The inflorescences, flowers and the vascularization of floral parts of Hedycarya arborea and Laurelia novae-zelandiae were described and comparisons made with other members of the family in an attempt to determine the basic types of inflorescences, flowers and floral vascularization in the family. The vegetative, inflorescence and floral meristems of the two genera were compared. It was concluded that the vegetative apices of both had the tunica-corpus configuration typical of many other woody Ranales and other orders. The inflorescence apices were quite similar to the vegetative ones. The young floral apices are in a state of transition from a tunica-corpus to a mantle-core configuration and older floral apices had the mantle-core configuration, which is typical of the floral apices of many woody Ranales. Unusual features of the floral apices of Hedycarya and Laurelia were the lack of a pronounced rib meristem and the occurrence of relatively frequent divisions within vacuolate cells of the core. The ontogeny of the stamens of Hedycarya and Laurelia was described and comparisons were made. In both genera the micro-sporangium developed in a similar fashions: in Hedycarya 5-6 wall layers are formed inside the epidermis; in Laurelia there are 3-5 layers. Both genera had a typically thickened endothecium and a tapetum of the secretory type in which the tapetal cells become binucleate during the first meiotic division of the pollen mother cells. In Hedycarya the meiotic divisions of the pollen mother cells are of the successive type in which walls form by means of centrifugal cell plates Pollen grains remain in permanent tetrads in this genus. In Laurelia wall formation at the end of meiosis is of a modified simultaneous type, which may not have been hitherto described in the literature. Pollen grains are not in permanent tetrads. When the first division occurs in each microspore in Hedycarya, all four cells of a tetrad are at the same stage of division and the generative cell is cut off towards the distal face of the grain. Each microspore is in the two celled condition when shed. It was deduced that the generative cell is cut off against what represents a radial wall of the grain (with reference to the tetrad stage) in Laurelia. Pollen is shed in either the two or three celled condition. Comparisons were made with the development of microsporangia and male gametophytes in other woody Ranales. A study was made of the ontogeny, structure and function of the staminal appendages of Laurelia. It was found that the appendages function as nectaries, the nectar being predominantly sucrose. After a discussion of the various theories as to the morphological nature of the staminal appendages of the Laurales, it was concluded that they are morphologically staminodes. The carpels of Hedycarya and Laurelia have a basically similar ontogeny in which, as in the Lauraceae, the terminal stigmatic region develops from a solid terminal meristem in contrast to many woody Ranales in which the stigma-consists of crests which surround the external part of the cleft of the carpel. The ovules of Hedycarya and Laurelia resemble those of most other woody Ranales in being bitegmic, crassinucellate and anatropous with a monosporic 8-nucleate embryo sac of the Polygonum type. Both linear and T-shaped megaspore tetrads were found in the two genera. Laurelia has pseudocarps which develop after anthesis and enclose plumose achenes, but in Hedycarya the fruits are drupes. It was concluded that Laurelia and Hedycarya belong to two subfamilies which have been separated from each other for a long time and have undergone considerable evolution in different directions. It was also concluded that the Monimiaceae are closely related to the Lauraceae.</p>

Floral morphology and the development of gamethophytes in Eucalyptus melliodora A. Cunn

1968 ◽  
Vol 16 (1) ◽  
pp. 19 ◽  
Author(s):  
GL Davis
Keyword(s):  
Soviet Union ◽  
Floral Morphology ◽  
Embryo Sac ◽  
Pollen Grains ◽  
The Black Sea ◽  
Anther Wall ◽  
Polygonum Type ◽  
Threefold Increase ◽  
The Soviet Union ◽  
Sea Area

Flower buds are first recognizable in late December at the commencement of new growth, and the deciduous bracts enclosing each cyme are shed about 3 weeks later. The buds increase rapidly in size, but anthesis does not occur until the end of September and the seeds are not shed from the capsules until the following August. The development of the double operculum and the floral parts is traced. Archesporal tissue is differentiated in the anthers in late February but ovule primordia are not formed until the end of March, by which time the stamens have reached their full size and anther wall formation is well advanced. In each bud events in the anthers and ovules are broadly comparable, but variation in the stages of development occurs between buds on the same branch. Meiosis takes place during the winter months, and embryo sac development follows the Polygonum type. The components of the egg apparatus undergo a threefold increase in size after their formation and, whereas the egg contains little cytoplasm, the synergids become densely cytoplasmic and laterally hooked. The pollen grains are two-celled when they are shed through the slits at the apices of the anthers. A comparison is made of the embryology of E. melliodora and that of species cultivated in Italy and the Black Sea area of the Soviet Union.

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.

Embryo sac and early ovule development in Oryzopsis miliacea and Stipa tortilis

1970 ◽  
Vol 48 (1) ◽  
pp. 27-41 ◽  
Author(s):  
Jack Maze ◽  
Lesly R. Bohm ◽  
Lyle E. Mehlenbacher Jr.
Keyword(s):  
Cell Division ◽  
Pollen Tube ◽  
Nuclear Division ◽  
Outer Integument ◽  
Embryo Sac ◽  
Ovule Development ◽  
Polygonum Type ◽  
Embryo Sac Development

The ovules of Stipa tortilis and Oryzopsis miliacea are hemianatropous, bitegmetic, and pseudocrassinucellate (sensu Davis 1966). The hemianatropous shape of the ovule is the result of characteristic patterns of cell division and enlargement in the chalazal area and areas alongside the embryo sac. Embryo sac development in both is Polygonum-type and both have proliferating antipodals. Endosperm is nuclear, although in O. miliacea it is atypical in that nuclear division is synchronous within one portion of the embryo sac, e.g. micropylar, but not synchronous between different portions of the embryo sac, e.g., micropylar and chalazal. Differences in ovule initiation, persistence of the outer integument, fate of the inner integument, nature of the nucellus, shape of the embryo sac, nature of the synergids, cytoplasm of the egg, polar nuclei, and endosperm exist between these two taxa. Both synergids of O. miliacea undergo changes before fertilization and one degenerates before fertilization. The pollen tube enters the embryo sac at the base of the persistent synergid. There is presently insufficient embryological data to permit meaningful speculation on relationships between Stipa and Oryzopsis. Embryologically, Stipa and Oryzopsis are festucoid grasses, as much other evidence indicates. Embryo sac development in the Gramineae is more similar to that of the Restionaceae than to that of the Cyperaceae. This is in contradiction to recent speculations on the relationships of the Gramineae.

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.

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