An Embryological Study of Kava, Piper methysticum

1994 ◽  
Vol 42 (2) ◽  
pp. 231 ◽  
Author(s):  
N Prakash ◽  
JF Brown ◽  
YH Wang
Keyword(s):  
Embryo Sac ◽  
Subsequent Development ◽  
Pollen Grains ◽  
Mature Embryo ◽  
Embryological Study ◽  
Anther Wall ◽  
Piper Methysticum ◽  
Male Flowers ◽  
Viable Seeds ◽  
Fruit Formation

An embryological study of Piper methysticum Forster f. (Piperaceae), undertaken to identify the probable cause for the absence of fruits in cultivated varieties, has revealed that the majority of plants in all the cultivars examined bore only male flowers. The anthers are tetrasporangiate and the anther wall comprises a well-developed endothecium with fibrous thickenings, two middle layers and a glandular tapetum. Meiosis is normal and simultaneous cytokinesis leads to tetrahedral microspore tetrads. Pollen degeneration was observed but was of very rare occurrence. The pollen grains are released when they are 2-celled and appear to be healthy and capable of germination. The unilocular ovary contains a single basal ovule which is orthotropous, bitegmic, and crassinucellar. Both integuments contribute to the formation of the micropyle. The development of the female gametophyte conforms to the tetrasporic Fritillaria-type. No abnormalities were noticed either in meiosis of the megaspore mother cell or in subsequent development leading to the formation of the mature embryo sac. Occasional parthenocarpy was observed but without viable seeds being present inside. It is suggested that, although the lack of fruit formation in this species is not because of any deficiencies in its embryological development, it may be due to a simple self-incompatibility mechanism.

An embryological study of Bauera capitata with comments on the systematic position of Bauera

1977 ◽  
Vol 25 (6) ◽  
pp. 615 ◽  
Author(s):  
N Prakash ◽  
EJ McAlister
Keyword(s):  
Outer Integument ◽  
Embryo Sac ◽  
Mature Embryo ◽  
Systematic Position ◽  
Embryological Study ◽  
Anther Wall ◽  
Polygonum Type ◽  
Antipodal Cells

In Bauera capitata Ser. ex DC. the anthers are tetrasporangiate with a three- or four-layered anther wall. The tapetum is glandular and its cells remain uninucleate. Tannin accumulates in the epidermis and the endothecium, and many connective cells in addition contain druses. Simultaneous cytokinesis leads to tetrahedral and isobilateral tetrads of microspores. The pollen is shed when two-nucleate and is gorged with starch. Degeneration of contents of one or more sporangia is frequent. The ovules are anatropous, crassinucellar and bitegmic. Twin microspore tetrads and twin embryo sacs are common but only one embryo sac reaches maturity. The development of the embryo sac follows the monosporic, Polygonum type. Starch accumulates in the mature embryo sac and remains until the initiation of endosperm. The antipodal cells persist until fertilization and rarely multiply. The seeds are frequently sterile but contain a well-formed outer integument. The healthy seeds have in addition a five- or six-layered inner integument, a nuclear type of endosperm and an embryo. The embryological evidence points to a closer affinity of Bauera Banks ex Andr. to the Cunoniaceae than to the Saxifragaceae.

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.

Apomixis and abnormal anther development in Calotis lappulacea Benth. (Compositae)

1968 ◽  
Vol 16 (1) ◽  
pp. 1 ◽  
Author(s):  
GL Davis
Keyword(s):  
New South ◽  
Embryo Sac ◽  
Pollen Grains ◽  
Anther Wall ◽  
Male Gametes ◽  
Globular Stage ◽  
South Wales ◽  
Vertical Division ◽  
Endosperm Formation ◽  
Embryo Sac Formation

A comparative study was made of material collected from four localities in New South Wales and Queensland and a number of embryological aberrations were found to be common to all districts. During microsporogenesis, certain tapetal cells not only failed to contribute to the tapetal periplasmodium but, after increasing in size, they separated from the anther wall and resembled one-, two-, or four-nucleate embryo sacs developing among the microspores. In one anther a structure was present which was very similar to a fully differentiated embryo sac. Although the pollen grains of some anthers contained male gametes, most anthers dehisced when the pollen was two-celled and some shrivelled soon after meiosis. Megasporogenesis was followed by the formation of linear tetrads of megaspores, but embryo sac formation was the result of somatic apospory and C. lappulacea appears to be an obligate apomict. The enlarging somatic cell usually invades the nucellar lobe and replaces the megaspores but one or more such celis commonly develop also in the chalaza, and up to eight embryo sacs were found in one ovule. Enlargement of a chalazal embryo sac sometimes resulted in penetration of the ovular epidermis and its invasion of the loculus as a haustorium-like structure. Extrusion of a developing embryo sac through the micropyle was common. Embryogeny is of the Asterad type, but vertical division of the terminal cell ca was delayed until after the basal cell cb had given rise to superposed cells m and ci. Polyembryony was common but only one embryo in each ovule reached maturity. Endosperm formation was independent of embryogeny but unless it was initiated before the globular stage of the embryo, the embryo sac collapsed and the embryo degenerated.

scholarly journals A Cytological Study of Anther and Pollen Development in Chinquapin (Castanea henryi)

HortScience ◽  
2020 ◽  
Vol 55 (6) ◽  
pp. 945-950
Author(s):  
Weiping Zhong ◽  
Zhoujun Zhu ◽  
Fen Ouyang ◽  
Qi Qiu ◽  
Xiaoming Fan ◽  
...  
Keyword(s):  
Pollen Development ◽  
Lipid Droplets ◽  
Morphological Characteristics ◽  
Pollen Grains ◽  
Middle Layer ◽  
Anther Development ◽  
Mature Pollen ◽  
Anther Wall ◽  
Male Flowers ◽  
Microspore Stage

The normal development of anthers and the formation of functional pollen are the prerequisites for successful pollination and fertilization. In this study, we observed dynamic changes in inflorescence and anther development in the chinquapin (Castanea henryi) using stereomicroscopy, light microscopy, and transmission electron microscopy. We found that cytokinesis during meiosis in microsporocytes was of the simultaneous type, and that the tetrads were mainly tetrahedral. Mature pollen grains contained two cells with three germ pores. The anther wall was of the basic type and composed of epidermis, endothecium, middle layers, and tapetum. Mature anthers had no middle layer and tapetum. The tapetum was of the glandular type. At the early microspore stage, a large number of starch granules appeared in the endothecium, which was deformed at the late microspore stage. Lipid droplets appeared in tapetum during the early microspore stage, and a few lipid droplets were still found during tapetum degeneration. The mature pollen accumulated a large amount of starch and lipids. These findings demonstrated that the anther wall provides nutrients and protection for pollen development. There is relatively stable correspondence between the external morphological characteristics of male flowers and internal structure of anther development.

scholarly journals Embriología de Erythroxylum havanense Jacq. (Erythroxylaceae)

2017 ◽  
pp. 25
Author(s):  
Sonia Vázquez-Santana ◽  
César A. Domínguez ◽  
Judith Márquez-Guzmán
Keyword(s):  
Seed Coat ◽  
Embryo Sac ◽  
Pollen Grains ◽  
Endosperm Development ◽  
Anther Wall ◽  
Starch Grains ◽  
Reproductive Structures ◽  
Exine Sculpturing ◽  
Erythroxylum Havanense ◽  
Mature Anther

We studied the development of reproductive structures in pin and thrum morphs of Erythroxylum havanense. The young anther wall consists of an epidermis, endothecium , 1-3 middle layers anda binucleate secretory tapetum. The mature anther wall has only two layers: epidermis and endothecium. Microspore tetrads are tetrahedral or isobilateral. Mature pollen grains are tricolporate, bicellular and contain starch grains. Exine sculpturing is verrugate in thrum pollen and reticulate in pin pollen. The ovule is sessile, pendulous, anatropous, bitegmic and crassinucellate. The embryo sac is heptacellular. An endothelium is differentiated. The endosperm development is nuclear, and the basal part of the nucellus persists during early endosperm development. Both integuments form the seed coat.

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.

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.

scholarly journals Embryology and fertility of the natural tetraploid Lessingianthus plantaginoides (Asteraceae, Vernonieae): taxonomic implications

Rodriguésia ◽  
2021 ◽  
Vol 72 ◽  
Author(s):  
Yanina de Jesús Pérez ◽  
Maria Betiana Angulo ◽  
Ana Honfi ◽  
Massimiliano Dematteis
Keyword(s):  
Embryo Sac ◽  
Pollen Grains ◽  
Anther Wall ◽  
Meiotic Analysis ◽  
Polygonum Type ◽  
Male And Female ◽  
Ontogenetic Study ◽  
Colonization Potential ◽  
Taxonomic Implications ◽  
Anther Wall Development

Abstract Lessingianthus plantaginoides (Vernonieae, Asteraceae) is a small natural tetraploid shrub that inhabits rocky highlands from South America. The population studied inhabits and covers an extensive region of a private reserve with high local biodiversity and animal and plant endemisms. With the purpose of providing insights into the cyto-embryology of this tetraploid species, the aims of this study were: to perform an ontogenetic study of the male and female gametophytes of L. plantaginoides; to carry out detailed meiotic analysis and evaluate the fertility of this species; to document and provide highlights on taxonomic implications of their reproductive aspects. Lessingianthus plantaginoides presented the following male and female gametophyte traits: dicotyledonous type of anther wall development, tetrahedral tetrads, 3-celled mature pollen grains; development of the chalazal megaspore, monosporic embryo sac and Polygonum type of megagametophyte development. The meiotic behavior was regular, the spores were tetrads of equal size and the pollen grains were highly stainable. Lessingianthus plantaginoides is a highly diplodized autotetraploid that reproduces sexually and has high meiotic regularity; which is apparently responsible for its colonization potential. It now seems certain that polyploid speciation plays a significant role in the establishment and diversification of the genus.

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.

Sign in / Sign up

Export Citation Format

Share Document