ISSN:0017-3134    

DOI:10.1080/00173139009429971

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

ISSN:0017-3134    

DOI:10.1080/00173139009429972

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Behaviour of elongating pollen tubes in the upper style ofGrevillea banksiiis described. Two populations of cytoplasmic vesicles (large and small) and early stages of callose plug formation were observed. No disfunction of self-tubes was noted that suggested incompatibility rejection. Burst tubes on stigmatic surfaces appear unrelated to incompatibility. Stigmatic and transmitting tissues are unaffected by passage of pollen tubes except for cells in direct contact which may appear crushed. Selfed flowers set seed in a field trial; emasculated ones, despite early swelling of the ovary in some, aborted within 8 wk. Reduction of tube number to two, equal to the number of ovules in the ovary, is attributed to heavier competition as the transmitting tissue narrows basally. In late stages of pollen tube interaction with the ovary, haustorial connections with ovary wall tissues occur, probably of post-fertilisation origin. Such distinct features of growth and ultrastructure as were seen are likely to be of adaptive rather than phylogenetic origin.

ISSN:0017-3134    

DOI:10.1080/00173139009429973

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

This is the second of two papers dealing with pollen morphology and evolution within the tribe Embothrieae. The present paper examines pollen of the subtribe Embothriinae,Embothrium(1 sp.),Oreocallis(6 spp.),Telopea(4 spp.)) in the light microscope and scanning and transmission electron microscopes. Pollen is large-sized, oblate to suboblate to oblate-spheroidal, foveolate to microreticulate to spinulate with a predominantly granular exine and simple aperture morphology. The Embothriinae are palynologically heterogeneous with bothOreocallisandTelopeaeach exhibiting two distinct pollen types. Pollen of New WorldOreocallis (O. grandiflora, O. mucronala) and the Old WorldO. pinnataare closer to the Old WorldTelopea(excludingT. speciosissima) than to other Old WorldOreocallis (O. sp. nov.O. brachycarpa, O. wickhamii). Within this complex,O. pinnataoccupies an intermediate position betweenOreocallisandTelopea. Despite the uniformly biporate condition inEmbothrium, other pollen characters support its inclusion in Embothriinae with close ties toOreocallis. Analysis of pollen trends within the tribe reveal: (1) an increase in pollen size; (2) a trend towards more spheroidal pollen; (3) the independent developments of biporate pollen inEmbothrium, OreocallisandLomatia; (4) independent developments of recticulate and spinulate sculpturing from a tectate-perforate exine; (5) loss of columellae; and 6) independent developments of complex modified postvestibulate and simple thickened-lamellate aperture morphologies.

ISSN:0017-3134    

DOI:10.1080/00173139009429974

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Harmomegathy was investigated inDiflugossa colorata, Peristrophe speciosa, andSchaueria calycotricha(Acanthaceae) using a SEM with cryo-stage facility. Hydrated pollen from undehisced anthers was compared with relatively dehydrated pollen from naturally dehisced anthers and with acetolysed pollen examined by conventional techniques. The observations suggest that pseudocolpi do not always play the same role in harmomegathy and do not necessarily function in the same way as colpori.Diflugossaexhibits a previously undescribed harmomegathic mechanism. The taxonomic significance of the observations are discussed.

ISSN:0017-3134    

DOI:10.1080/00173139009429975

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

A 2-year study of pollen influx in 37 Tauber traps along a 320-km transect extending from 1–224 to 3642 m elevation indicates that pollen dispersal occurs both upslope and down-slope in the southern Rocky Mountains. The dispersal pattern is related to both westerly airflow over the mountain crest and south and southwest summer winds. Tree taxa exhibit a greater variability in pollen production, from one year to another, than shrubs and grasses. Higher pollen percentages generally correspond to greater influx values.Abies, Picea, andPinuspollen influx correlate with tree absolute density (trees per hectare). Montane species ofAbiesandPiceaare under-represented in pollen percentages, whilePinusspecies are over-represented, as in eastern North America. Aspen trees dominate several forest stands, butPopulusis a minor component of pollen trap assemblages. Between 20 and 60% of the pollen grains deposited in the traps has originated by medium- or long-distance transport.

ISSN:0017-3134    

DOI:10.1080/00173139009429976

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Fifty-four living moss samples from various regions in Spitsbergen were studied for pollen and spores; the results are compared with descriptions made of the surrounding vegetation. Problems connected with the study of pollen production and dispersal, specific for the high Arctic are discussed. The regional deposition of the various pollen types could be classified as low, very low, or absent. The local pollen representation of plant species (expressed as the ratio: pollen percentage based on a local pollen sum/plant cover as percentage of total vascular-plant cover) could, in spite of large differences between sites, be established approximately for many pollen types and for some types was found to vary between regions in Spitsbergen. A good relation between distance of plants from sampling sites and pollen percentages calculated on a long-distance pollen sum was found forSalix polaris, but not forSaxifraga oppositifolia.

ISSN:0017-3134    

DOI:10.1080/00173139009429977

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

To determine the best date for patients in the southern part of the Netherlands to begin treatment for pollinosis, an attempt was made to predict the start of the grass pollen season at Helmond as accurately as possible, as was previously done at Leiden. The start of the grass pollen season was defined as the date when at a given location the accumulated total (from 1 Jan.) of 24 h average grass pollen concentrations (No./m3) reaches 100 (the so-called Σ100-method). Using the phenological method over the years 1981 through 1985, with the birch (Σ125=x) as the indicator plant, the start of the grass pollen period (Σ100=z) could be predicted much more accurately than would have been possible solely on the basis of the mean starting dates in the preceding years. The predicted starting date (z) can be calculated with the equationz=0.44x+95.46 (xandzas day-of-year numbers), SD=3.6 days,r=0.83,n=5). The SD of the Σ100-method of grasses being 5.6 days, the effectivity of the prediction is 35.7%. The difference in results between Helmond and Leiden is discussed.

ISSN:0017-3134    

DOI:10.1080/00173139009429978

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The occurrence of airborne fungi at an urban coastal site was compared with that at a rural inland site in the South of Sardinia. Spore concentrations at the two sites differed markedly with lower concentrations at the urban site but the spore types found were similar. The general trend of the fungal airspores was also very similar at both sites as a result of the similar climatic conditions.

ISSN:0017-3134    

DOI:10.1080/00173139009429979

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

ISSN:0017-3134    

DOI:10.1080/00173139009429980

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor