摘要:

The taxoid type of pollen has a pore in the exine, plugged by an opercule-like structure, the operculoid, as seen under scanning electron microscope. In light microscopy a bulge at the surface of the exine is evident only when using a fluorochrome (calcofluor). The bulge, which is part of the intine, appears fluorescent in mature pollen grains. In water, it disappears progressively within one to two minutes. It is assumed that the operculoid is ejected because of the swelling of the intine in the apertural region following contact with water. Therefore, the exine aperture constitutes a passage for the water to penetrate towards the whole intine. The mucilagenous substance of the intine is hydrated and dilated and causes the bursting of the exine which is left in the medium. The mode of exine rupture in the pollen ofCupressus arizonicaandJuniperus communiswas studied and a possible explanation of the function of the apertural structure is proposed.

ISSN:0017-3134    

DOI:10.1080/00173138209427673

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

Two of the thirteen species ofHedycaryaof the family Monimiaceae have pollen in permanent tetrads. In the New Zealand species,Hedycarya arborea, the nascent generative cell is formed at the distal pole of each grain, but in the Australian species,Hedycarya angustifolia, it arises at the junction of the internal (lateral) and external (distal) wall of each microspore. Synchronous division into vegetative and generative nuclei, within each tetrad of both species, is attributed to the presence of cytoplasmic connections between individual grains. It is suggested that the position of the nascent generative cell inH. angustifoliarepresents the ancestral condition and that the polar position arose with the evolution of a thickened distal polar exine inH. arboreawhich produced a broad apertural region encircling this polar cap.

ISSN:0017-3134    

DOI:10.1080/00173138209427674

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

The pollen of several species of the generaBagassa, Batocarpus, Broussonetia, Cardiogyne, Chlorophora, Madura, CudraniaandPlecospermumhave been studied. These genera form a «cluster» in the tribe Moreae and pollenmorphological data confirm the taxonomic suggestion that the genera are more or less related. However, pollen grains ofMaclura pomiferadiffer largely whereas those ofMaclura brasiliensisagree with the general description of the other pollen grains.

ISSN:0017-3134    

DOI:10.1080/00173138209427675

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

Pollen from several different interspecific F, hybrids inHibiscusL. sectionFurcariaDC (Malvaceae) was studied. Morphological features segregated in several hybrids, indicating that the haploid spore genome does contribute information for exine patterning. Also, in the one set of reciprocal hybrids available, reciprocal differences appeared. That suggests that maternally-inherited factors may also be involved in the control of exine morphology.

ISSN:0017-3134    

DOI:10.1080/00173138209427676

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

Pollen grains of 13 species and varieties investigated withinCoffeaL. (Rubiaceae) were found to be highly polymorphic. The majority are members of the Section Eucoffea, and two species belong to the Section Paracoffea.Coffea arabicaL. andC. eugenioidesMoore show the highest degree of polymorphism.

ISSN:0017-3134    

DOI:10.1080/00173138209427677

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

Expressipollis striatusandAnacolosidites striatusare new Upper Cretaceous (Campanian) pollen species described from arctic Alaska.E. striatusappears to evolve intoA. striatusin less than 100 feet of stratigraphic section, and this change is noted by the apparent modification of a syndemicolpate pollen aperture to a hexaporate pollen aperture in successive outcrop samples.

ISSN:0017-3134    

DOI:10.1080/00173138209427678

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

The diagnosis of the dinoflagellate cyst genusSarjeantiaHorowitz is revised so as to incorporate information on its cavation and method of excystment. Examination of the other microfossils (acritarchs, miospores and dinoflagellate cysts) present with the holotype in the type slide suggests a much younger date than that hitherto assigned to it, probably Middle Jurassic (upper Bathonian) rather than Upper Triassic.

ISSN:0017-3134    

DOI:10.1080/00173138209427679

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

Statistical models to predict daily airborne pollen concentration from meteorological conditions have been evaluated using several years' data from Stockholm. ForBetulapollen values for the multiple correlation coefficient (R) were up to 0.8 using a model describing the seasonal course as well as the day-to-day variation. Models of this kind cannot interpret causally pollen variation. However, the daily temperature values from early spring have a large influence on the time of the beginning of the pollen season and also on the subsequent day-to-day variation. Based on this study, pollen forecasts have been initiated in Stockholm in the spring of 1981.

ISSN:0017-3134    

DOI:10.1080/00173138209427680

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

This is a scanned image of the original Editorial Board page(s) for this issue

ISSN:0017-3134    

DOI:10.1080/00173138209427672

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor