摘要:

Pollen of Australian species ofParsonsia(Apocynaceae) was investigated with LM, SEM and TEM. In external morphologyParsonsiapollen is typical of the subfamily Apocynoideae, being spherical, with a smooth or finely wrinkled surface and is mostly triporate. Differences in pollen size were found between some species, with diameters ranging from 19 um-55 pm. Also differences in the number of apertures per grain, with invariably 3 in one species, 4 in another and, depending on the species 2 and 3; 2, 3 and 4; 3, 4 and 5; 3,4, 5 and 6, in others. Pollen ultrastructure had some features previously unreported in the family. The exine consists of a tectum with an almost smooth surface, containing microperforations, overlying an infratectum which under TEM appears to consist of several uneven layers of tangentially aligned plate-like lamellae. However, use of the ion beam etching technique to strip off the tectum and enable examination of the surface of the infratectum under SEM, as well as examination of the internal surface of the exine of fractured acetolysed grains, showed that the infratectum consisted of an intricate three-dimensional network of anastomosing cylindrical elements of somewhat varying diameter. In some taxa, there is an inner infratectum of inwardly protruding, large oval granules. A foot layer (sole) is absent, but a thin endexine is apparent. Non-apertural intine is 3 layered in some species, a feature not previously reported for the Apocynaceae. In other species the intine has 1 or 2 layers. The ectexine reaches maximum thickness within the annulus surrounding the aperture and becomes thin and fragmented on the surface of the apertural membrane, which appears to contain a thin endexine. Five pollen types were recognized and comparisons made with published reports of pollen ultrastructure of other members of the family.

ISSN:0017-3134    

DOI:10.1080/00173139009427740

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The present cytopalynological study relates to the pollen morphology ofArachisL., comprising diploid wild species, tetraploid species including the cultivatedA. hypogaea(ground nut), diploid interspecific hybrids, and triploids and hexaploids of cultivars ofA. hypogaeaand of diploid wild species. In general, the pollen grains are 3-zonocolpate and reticulate/fossulate and trends in pollen variations have been noticed with regard to aperture and exine ornamentation. The size, shape and number of lumina (per unit area) as seen in SEM picture have provided the basic parameter for taxonomic differentiation of the species and even cultivars (in the case ofA. hypogaea), and in the assessment of inheritance pattern in the hybrids.

ISSN:0017-3134    

DOI:10.1080/00173139009427741

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Pollen grains of 49 species of Gramineae, most of them from the Venezuelan Andes, were studied. All the species, except one, have the characteristic grass pollen type. The pollen grain size ranges from 17.5 to 60.6 um (maximum diameter). Small differences in ornamentation together with size of grains enabled to distinguish groups or single species within the grass pollen type. Pollen ofPariana stenolemma(herbaceous bamboo) differs from all the others in having an areolate sexine and no annulus.

ISSN:0017-3134    

DOI:10.1080/00173139009427742

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The pollen grains of seven genera in the Cupressaceae were examined by means of light and scanning electron microscopy. The pollen is spheroidal, intectate, monoporate and scabrate, microverrucate to microgemmate. The uniformity of the pollen morphology supports the systematic unity of this family. The single pore with an annulus and the sexinous elements (orbicules) are here considered as the characteristic traits. A further subdivision at the generic or sectional level, based on pollen morphology, is impossible.

ISSN:0017-3134    

DOI:10.1080/00173139009427743

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Biological control ofPrimus serotina, a forest weed in the Netherlands, by means of the silverleaf fungusChondrostereum purpureumis studied. The fungus is a common saprophyte in dead wood. As a wound invader, it can cause silverleaf disease of P.serotinaand fruit trees. Biological control ofP. serotinawithin a forest leads to infection, sporulation and spore dispersal, and thus creates a risk to fruit trees outside the forest. To estimate this risk, spore immission was calculated by means of the Gaussian plume model (GPM). A short-term version of the GPM was used to calculate the ‘absolute risk’ as the spore density outside the forest due to biological control. Mean spore densities at 5000 m distance downwind of the forest were at least one order of magnitude lower than at 500 m. Maximum spore density at 5000 m downwind of the forest was calculated to be 32 spores.m-3, and at 500 m 141 spores.m-3. It was concluded that risk to fruit trees was appreciable at 500 m distance and negligible at 5000 m distance. The ‘relative risk’ was calculated as the ratio of added spore density, due to biological control, over natural spore density, due to normal presence ofC. purpureumin nature. A long-term version of the GPM was used for this purpose. Calculations were performed for the district of Olst using literature values for emission of natural sources. Added spore densities during the day (10-1spores.m-3) and at night (100spores.m-3) were of the same order of magnitude as the natural spore densities. It was concluded that the added risk to orchards in a rural area was about equal to the natural risk. Assumptions and approximations in the risk analysis and the merits of the GPM are discussed in view of the acceptability of biological control ofP. serotina.

ISSN:0017-3134    

DOI:10.1080/00173139009427744

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Atmospheric pollen was sampled from native vegetation at the Desert Laboratory, University of Arizona, Tucson, Arizona, USA, using a Burkard trap. The pollen counts disclosed two conditions of pollen preservation (1) pollen with the intine visible, and (2) pollen characterized either by loss of the intine or by a crumpled exine. The former was thought to be freshly discharged, the latter to be reentrained from depositional surfaces. 11% of the atmospheric pollen collected was reentrained. Winds accompanying convective summer storms enhanced pollen reentrainment. Chenopodiaceae-Amaranthusand Gramineae, morphologically smooth pollen taxa, totaled 86% of the reentrained pollen during 1981–82. Pollen from soils appeared to be a major source of reentrained pollen. The amount of reentrainment varied seasonally; reentrainment concentration was greatest during the summer, whereas, the percent of reentrained pollen was greatest during the winter. Pollen reentrainment has the potential to bias fossil pollen records in arid environments particularly in seasons when primary pollen production is low, e.g. winter.

ISSN:0017-3134    

DOI:10.1080/00173139009427745

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Concentrations of airborne spores of fungi and actinomycetes were investigated from 20 samples collected during the handling of wood chips by using a six-stage fractionating impactor (Andersen sampler). Ten samples were taken on wood chip piles or beside the chip conveyor belts of cellulose factories, and ten samples were taken beside chip conveyor belts in central heating plants of saw mills. The spore exposure level varied from 103to 106cfu/m3air. Wood chips used for cellulose production released large numbers of mesophilic and thermotolerant fungi, especiallyAspergillus fumigatus, indicating that spontaneous heating had occurred during the storage. By contrast, heavy exposure toPenicilliumspecies and other mesophilic fungi was characteristic of the handling of fuel chips, which are usually only stored for short periods in saw mills. The greatest spore concentration, 3×106cfu/m3air (mainlyPenicillium), was measured during the handling of fuel chips stored for four months. Heavy exposure to airborne spores may cause respiratory diseases, e.g. allergic alveolitis. The possible role ofHumicoia, RhizopusandStreptomycesspecies,Paecilomyces varioliiandTrichoderma viride, which occasionally occurred in high concentrations, should be investigated more thoroughly as etiological agents of respiratory symptoms among workers handling stored wood chips.

ISSN:0017-3134    

DOI:10.1080/00173139009427746

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Phenolic compounds present in the pollen grains ofAreca catechu, Phoenix sylvestris(Fam. Arecaceae),Treme orientalis(Fam. Urticaceae) andShorea robusta(Fam. Dipterocarpaceae) showed wide diversity in their chromatograms with respect to both colour and hRfvalues. This diversity has also been observed in pollen morphology. Potentialities of the utilization of phenolic compounds present in the pollen grains may be demonstrated in understanding phylogenetic relationship and plant affinity.

ISSN:0017-3134    

DOI:10.1080/00173139009427747

出版商:Taylor & Francis Group    

年代:1990

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:10.1080/00173139009427739

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor