摘要:

InDacrycarpus dacrydioides(Rich.) De Laubenfels (Podocarpus d.) study of the arrangement of the microspores at the tetrad stage reveals that the two pairs of sister-microspores cross at an angle of about 90°, and each microspore has one apex of its triangular aperture orientated towards the sister-microspore and the other two apices face the opposite direction. Consequently, the twelve aperture apices of the tetrad meet two and two at six points. At the first stage of development the rugulate processes on the proximal face observed in SEM are very marked, and the arms of the triradiate ridge are pronounced and sinuous; at the further stages, however, the sexine of the central part becomes more or less smooth, and the arms of the triradiate ridge become straight and less visible, or disappear. A hypothesis is proposed to tentatively explain this unusual sculptural development.

ISSN:0017-3134    

DOI:10.1080/00173138309429907

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Pollen of 10 species ofAcanthopanaxwas examined by light, scanning and transmission electron microscopy. The TEM study has confirmed the previous interpretation of nexine structure for Araliaceae. Three sexine sculpture patterns were recognized. Perforaterugulose type appears to be the basic sexine pattern for the genus. The other two types are reticulate and reticulate with a sublayer of tectum. The rhomboidal pollen shape and basic sexine pattern ofAcanthopanaxresemble closely thehoitype of the related genusSchefflera.

ISSN:0017-3134    

DOI:10.1080/00173138309429908

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

An attempt is made to investigate the sculpture of JapaneseCastanopsispollen with SEM. The grains ofC. cuspidatavar.cuspidataandC. cuspidatavar.sieboldiihave the same sculptural pattern which is tangled-stringy-rugulose, but the former has finer and more densely crossed elements than the latter. The fossil pollen grains ofC. cuspidataare of two types, which is completely in accordance with the modern pollen of the two varieties.

ISSN:0017-3134    

DOI:10.1080/00173138309429909

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Thirty-two species from 17 genera were examined by scanning electron microscopy and representatives from each subfamily were examined by transmission electron microscopy. The treatment of Ulmaceae based on pollen grains is consistent with the treatment of the family presented by I. A. Grudzinskaya. Wall structure and exine sculpturing are the best diagnostic pollen characteristics for determining subfamilial affinities. The pollen morphological characteristics of the Celtidoideae are more like those of Moraceae than of Ulmoideae, thus lending support to Grudzinskaya's suggestion that the Celtidoideae should have familial status and occupy a phylogenetically intermediate position between the Ulmaceae (Ulmoideae) and the Moraceae.

ISSN:0017-3134    

DOI:10.1080/00173138309429910

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

While screening 45 samples of pollen suspension for their antifungal activity againstHelminthosporium oryzaeandAlternaria alternata, only that ofLycopersicon lycopersicumexhibited absolute toxicity against both the pathogens. The maximum inhibitory dilutions were found to be 1: 200 and 1: 500 (w/v) againstA. alternataandH. oryzaerespectively. The other pollen suspensions exhibited varying degrees of mycotoxicity. The temperature and autoclaving had no adverse effect on the mycotoxicity of the pollen suspension.

ISSN:0017-3134    

DOI:10.1080/00173138309429911

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Sarjeantia triassicaHorowitz, 1975 (Dinophyceae) from the Lower Saharonim Formation (Anisian-Ladinian) in Zohar 8 borehole, southern Israel, shows a morphology representative ofAratrisporites fimbriatus(Klaus, 1960) Playford & Dettmann, 1965 (Sporites, Monoletes).

ISSN:0017-3134    

DOI:10.1080/00173138309429912

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Cette étude est la deuxième d'une série concernant les associations sporo-polliniques préquaternaires de l'Egypte. Dans cet article sont présentés les Longiaxes, et les grains de pollen fenestrés des angiospermes, puis les grains de pollen remaniés. 2 fgen. nouveaux, et 7 espèces de forme nouvelles sont décrites. Les pourcentages des groupes de pollens importants du point de vue de l'histoire de la végétation indiquent qu'il n'y a pas eu de changement important dans la végétation et le climat, à partir du Miocène inférieur, jusqu au Plio-Pleistocène. La végétation était caractérisée en premier lieu par des plantes herbacées; Chenopodiacées et Graminées, qui signalent une végétation semidésertique — steppique. Ce type de végétation est connu dans quelques régions de l'URSS, et diffère fondamentalement de celui de l'Europe Centrale, Occidentale et de l'extrême Orient; il est caractérisé par les Taxodiaceae-Cupressaceae, Myricaceae, Cyrillaceae, ainsi queQuercus, Taxodium, Pinus, Cunninghamiadonc des arbres et des arbustes en général. En se basant sur les données palynologiques, une zone désertique allant de l'Est de l'Afrique du Nord jusqu'à l'Asie Moyenne et la partie orientale de l'Europe a divisé en deux la végétation forestière de l'Eurasie. II n'y a pas de différence importante dans la composition pollinique de la zone désertique de l'Eurasie et de l'Afrique du Nord, pendant le Néogène.

ISSN:0017-3134    

DOI:10.1080/00173138309429913

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Pollen rainsplashed from the collar of the Tauber trap could augment significantly the catch due to direct deposition. To test for rainsplash error under natural conditions, Tauber traps were paired in the field with simple jar traps without collars. Relative pollen catches during dry weather would have established a performance ratio between these types of trap (attributable solely to differences in their aerodynamic efficiency) but rain during all sampling periods unfortunately precluded this comparison. The average pollen catch per sampling period was consistently higher in the Tauber trap than in the jar trap, despite variations in weather. However, differences in pollen catch between the two traps in a pair were always lowest under trees where, paradoxically, maximum rainsplash error was expected (but where wind speeds were low), and highest in the centre of a lake (where wind speeds were higher). These results suggest that higher pollen catches in the Tauber trap than in the jar trap were due to a discrepancy in performance between the traps in moving air rather than to extra pollen being splashed by rain into the Tauber trap, for which error no conclusive evidence was found.

ISSN:0017-3134    

DOI:10.1080/00173138309429914

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The pollen production for both years was three times higher in Basel than at Louvain-la-Neuve. The interpretation of the pollen calendars showed an average onset of eight days earlier in 1979 and five days earlier in 1980 for the taxa in Basel. The pollen catch for both stations was greater in 1980 than in 1979, which was characterized by an average delay in the onset of pollen shedding both in Basel and at Louvain-la-Neuve.

ISSN:0017-3134    

DOI:10.1080/00173138309429915

出版商:Taylor & Francis Group    

年代:1983

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:10.1080/00173138309429906

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor