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.

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.

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.

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 Desarrollo del gametofito femenino de Tagetes patula (Asteraceae)

2017 ◽  
pp. 5
Author(s):  
Marcelina García-Aguilar ◽  
E. Mark Engleman ◽  
Eulogio Pimienta-Barrios
Keyword(s):  
Seed Development ◽  
Early Development ◽  
Mother Cell ◽  
Megaspore Mother Cell ◽  
Embryo Sac ◽  
Tagetes Patula ◽  
Polygonum Type ◽  
Chalazal Megaspore ◽  
The Family ◽  
Apomictic Reproduction

The genus Tagetes reproduces sexually by seed, but recent morphological and hybridization studies in Tagetes patula suggest an apomictic type of reproduction (seed development without fertilization). In order to determine the sexual or apomictic origen of the embryo, we have studied megasporogenesis, megagametogenesis and the early development of the embryo. Tagetes patula L. has a typical ovule for the family Asteraceae: anatropous, unitegmic, tenuinucellate and with basal placentation. A single hypodermal archesporial cell develops directly as the megaspore mother cell. Megaspogenesis is normal and embryo sac develops from the chalazal megaspore. The embryo sac is of the Polygonum type. Female ray flowers show irregularities in megagametophyte development such as formation of more than eight nuclei, inverted polarity and incomplete differentiation of the megagametophyte cells in mature flowers. These irregularities do not necessarily prove apomictic reproduction in Tagetes patula.

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.

Reproductive development in two species of Darwinia Rudge (Myrtaceae)

1969 ◽  
Vol 17 (2) ◽  
pp. 215 ◽  
Author(s):  
N Prakash
Keyword(s):  
Embryo Sac ◽  
Pollen Grains ◽  
Reproductive Development ◽  
Outer Zone ◽  
Mature Embryo ◽  
Globular Embryo ◽  
Primary Endosperm Nucleus ◽  
Oil Glands ◽  
Polygonum Type ◽  
History Of

In Darwinia the floral parts are differentiated in a "calyx-orolla-gynoeciumandroecium" sequence. In individual buds stages of microsporogenesis markedly precede corresponding stages of megasporogenesis. The anther is tetrasporangiate with all sporangia lying in one plane. The secretory tapetum is one- to three-layered within the same microsporangium and a large number of Ubisch bodies are formed. The anthers dehisce by minute lateral pores and an ingenious mechanism helps disperse the twocelled pollen grains. A basal placenta in the single loculus of the ovary bears four ovules in D. micropetala and two in D. fascicularis. In both species, however, only one ovule is functional after fertilization. The fully grown ovules are anatropous, crassinucellar, and bitegmic; the inner integument forms the micropyle. The parietal tissue is most massive at the completion of megasporogenesis but is progressively destroyed later. The embryo sac follows the Polygonum type of developnlent and when mature is five-nucleate, the three antipodals being ephemeral. Following fertilization, the primary endosperm nucleus divides before the zygote. Subsequent nuclear divisions in the endosperm mother cell are synchronous and lead to a free-nuclear endosperm which becomes secondarily cellular, starting from the micropylar end at the time the globular embryo assumes an elongated shape. Embryogeny is irregular and the mature embryo is straight with a massive radicle and a hypocotyl which terminates in two barely recognizable cotyledons. Sometimes the minute cotyledons are borne on a narrow neck-like extension of the hypocotyl. A suspensor is absent. Both integuments are represented in the seed coat and only the outer layer of the outer and the inner layer of the inner integuments, with their thick-walled tanniniferous cells, remain in the fully grown seed. The ovary wall is demarcated into an outer zone containing oil glands surrounded by cells containing a tannin-like substance and an inner zone of spongy parenchyma. In the fruit this spongy zone breaks down completely but the outer zone is retained. The two species of Darwinia, while closely resembling each other in their embryology, differ significantly from other Myrtaceae. However, no taxonomic conclusions are drawn at this stage, pending enquiry into the life history of other members of the tribe Chamaelaucieae.

Embryological studies in the compositae, I. Sporogenesis, Gametogenesis, and Embryogeny in Cotula australis (Less.) Hook. F

1962 ◽  
Vol 10 (1) ◽  
pp. 1 ◽  
Author(s):  
GL Davis
Keyword(s):  
Mother Cell ◽  
Megaspore Mother Cell ◽  
Embryo Sac ◽  
Subsequent Development ◽  
Pollen Grains ◽  
Archesporial Cell ◽  
Polygonum Type ◽  
Wall Formation ◽  
Chalazal Megaspore

Cotula australis has a discoid heterogamous capitulum in which the outermost three whorls of florets are female and naked. The bisexual disk florets are fully fertile and have a four-lobed corolla with four shortly epipetalous stamens. The anthers contain only two microsporangia. Wall formation and microsporogenesis are described and the pollen grains are shed at the three-celled condition. The ovule is teguinucellate and the hypodermal archesporial cell develops directly as the megaspore mother cell. Megasporogenesis is normal and the monosporio embryo sac develops from the chalazal megaspore. Breakdown of the nucellar epidermis takes place when the embryo sac is binucleate and its subsequent development follows the Polygonum type. The synergids extend deeply into the micropyle and one persists until late in embryogeny as a haustorium. The development of the embryo is of the Asterad type, and the endosperm is cellular. C. coronopifolia agrees with C. australis in the presence of only two microsporangia in each anther and the development of a synergid haustorium.

scholarly journals Pollen characters as taxonomic evidence in some species of Dipsacaceae from Iran

2017 ◽  
Vol 24 (2) ◽  
pp. 129-136 ◽  
Author(s):  
Ebadi-Nahari Mostafa ◽  
Nikzat-Siahkolaee Sedigheh ◽  
Eftekharian Rosa
Keyword(s):  
Pollen Morphology ◽  
Pollen Grains ◽  
Pollen Grain ◽  
Pollen Type ◽  
Upgma Tree ◽  
Pollen Characters ◽  
Exine Ornamentation ◽  
The Family ◽  
The World ◽  
Plant Taxon

Pollen morphology of nine species representing four genera: Cephalaria Schrad, Dipsacus L., Pterocephalus Vaill. and Scabiosa L. of the family Dipsacaceae in Iran has been investigated by means of scanning electron microscopy (SEM). The results showed that pollen grains were triporate and tricolpate. The pollen type of Scabiosa rotata Bieb. (tri- and tetraporate) is the first report in the world. The sizes of pollen grains fall into the classification group magna (pollen grain diameter 50–100 μm). Pollen shapes vary from preoblate to prolate and their polar views were triangulate and lobate. The exine ornamentation varies from gemmate in S. rotata to spinulate in the rest studied species. Species of Scabiosa have been dispersed in UPGMA tree that this confirmed the previous studies about taxonomic problems and species complexity in this genus. These results show the transfer of the some Scabisoa species to Lomelosia Raf. based on palynological characters. Pollen morphology of the family is helpful at the generic and specific level.Bangladesh J. Plant Taxon. 24(2): 129–136, 2017 (December)

scholarly journals Pollen, Tapetum, and Orbicule Development inColletia paradoxaandDiscaria americana(Rhamnaceae)

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
M. Gotelli ◽  
B. Galati ◽  
D. Medan
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Pollen Grains ◽  
Pollen Grain ◽  
Ultrastructural Changes ◽  
Transmission Electron ◽  
The Family ◽  
Tapetal Cells ◽  
Grain Formation

Tapetum, orbicule, and pollen grain ontogeny inColletia paradoxaandDiscaria americanawere studied with transmission electron microscopy (TEM). The ultrastructural changes observed during the different stages of development in the tapetal cells and related to orbicule and pollen grain formation are described. The proorbicules have the appearance of lipid globule, and their formation is related to the endoplasmic reticulum of rough type (ERr). This is the first report on the presence of orbicules in the family Rhamnaceae. Pollen grains are shed at the bicellular stage.

Reproduction Multitasking: The Male Gametophyte

2021 ◽  
Vol 72 (1) ◽  
Author(s):  
Said Hafidh ◽  
David Honys
Keyword(s):  
Male Gametophyte ◽  
Cell Communication ◽  
Embryo Sac ◽  
Pollen Grain ◽  
Wall Structure ◽  
Annual Review ◽  
Publication Date ◽  
Developmental Phase ◽  
Double Fertilization ◽  
Male Gametes

The gametophyte represents the sexual phase in the alternation of generations in plants; the other, nonsexual phase is the sporophyte. Here, we review the evolutionary origins of the male gametophyte among land plants and, in particular, its ontogenesis in flowering plants. The highly reduced male gametophyte of angiosperm plants is a two- or three-celled pollen grain. Its task is the production of two male gametes and their transport to the female gametophyte, the embryo sac, where double fertilization takes place. We describe two phases of pollen ontogenesis—a developmental phase leading to the differentiation of the male germline and the formation of a mature pollen grain and a functional phase representing the pollen tube growth, beginning with the landing of the pollen grain on the stigma and ending with double fertilization. We highlight recent advances in the complex regulatory mechanisms involved, including posttranscriptional regulation and transcript storage, intracellular metabolic signaling, pollen cell wall structure and synthesis, protein secretion, and phased cell–cell communication within the reproductive tissues. Expected final online publication date for the Annual Review of Plant Biology, Volume 72 is May 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

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