摘要:

Pollen grains ofNelumbo caspicum(DC.) Fisch. grown in the hothouses of the Komarov Botanical Institute were investigated. Among normally developed pollen grains there were grains clustered in different kinds of tetrads. These individual changes suggest the course of the evolutionary transformations of the colpus structure. The investigations were carried out with both light- and electron microscope

ISSN:0017-3134    

DOI:10.1080/00173137909428864

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

The pollen grains of some genera related toTabernaemontana(Apocynaceae) were examined by means of light and electron microscopy. Some genera ought to be included inTabernaemontanawith reference to the general pollen morphology as well as to the fine sculpture of the inner exine surface.

ISSN:0017-3134    

DOI:10.1080/00173137909428865

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

The pantoporate, operculate pollen found inCranocarpus martiiis described using scanning and transmission electron microscopy. It is believed that this is the first report of this pollen type in the Leguminosae. Eight out of nine other taxa which are taxonomically related have tricolporate pollen whileBrya ebenus,the ninth species compared, shows some superficial similarities having usually 6-porate, operculate pollen. No definite taxo-nomic conclusions can be drawn from pollen morphology within the group

ISSN:0017-3134    

DOI:10.1080/00173137909428866

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

The mono- and diaperturate pollen grains have been found to be widely different in the orientation of apertures with regard to their polarity. The nature, position and polarity of eleven apertural types from widely unrelated taxa of angiosperms, have been studied in tetrad as well as in monad states, e.g. monosulcate (both ana- and catasulcate), extended-sulcate, sulculate, meridiono-sulculate, monoulcerate, disulcate, diulcerate, disulculate, diporate and dicolpate conditions. Illustrations have been provided to demonstrate the respective positions in tetrad conditions and equatorial and polar views in the monad condition. Avolutionary sequence transpires from these apertural types, from simple to more complex, which have been shown in a phylogenetic tree

ISSN:0017-3134    

DOI:10.1080/00173137909428867

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

The pollen size variations seen among the cultivars of Ananas comosus (Bromeliaceae) and the differences seen in wall reticulations of A. comosus and A. bracteatus are recorded. Among the different cultivars the pollen viability was between 24–92% according to the peroxidase and acetocarmine tests. With selfing, the pollen tubes grew to a maximum of about 13% of the stylar length in about eight hours after pollination. Results obtained, in two different media, regarding in vitro percentage germination and tube length are compared. The additions of various hormones and vitamins improved pollen tube growth but not germination. The reciprocal cross between cultivars resulted in seed formation, and the highest number of seeds was obtained with MasmerahxMauritius crosses. The results of the present study are compared with relevant literature

ISSN:0017-3134    

DOI:10.1080/00173137909428868

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

Morphological analysis of the spores and their bearing on the taxonomy and evolution of Pteridaceae have been dealt with. The spore morphological combinations in evolutionary successions are trilete-non-perinous, trilete-perinous, monolete-non-perinous and monolete-perinous. It is suggested that the levels of evolutionary progress of the various taxa are in the order of succession, Pteroids, Gymnogrammoids and Lindsaeoids, but each have evolved along parallel lines from the Dicksonioid-Dennstaedtioid complex.

ISSN:0017-3134    

DOI:10.1080/00173137909428869

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

Relative pollen composition during the monthly sedimentation of river seston at different points in the reservoirs of some hydroelectric stations in Finland has been studied. Samples were taken in 8 reservoirs in the water courses of Kemijoki, Oulujoki, Kokemäenjoki, Paimionjoki, Pielisjoki and the Höytiäinen channel in 1974. The relative pollen composition reflects generally the present vegetation and the forest composition of the drainage areas of the rivers investigated. Particularly Pinus, Betula and Picea seem to be little effected by the time of sedimentation. Knowledge of the pollenflora in the Finnish river material is for its part significant for the evaluation of the pollen composition of the surface samples of the Baltic sediments

ISSN:0017-3134    

DOI:10.1080/00173137909428870

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

The modern pollen deposition in high tropical mountains was studied by the pollen analysis of 18 surface samples collected between 3 100–4340m elevation. The relative value among the pollen types as well as the absolute value of the main types were estimated for each sample. Pollen and spore assemblages reflect well the vegetation types, and their distribution. Each type of páramo studied has a characteristic assemblage. The dispersion power and the quantity of deposition for the montane plants was evaluated by counting the number of grains per mg of sediment. The long-distance type are: Podocarpus, Hedyosmum, and psilate Cyathea (moderate dispersion power); Alnus (high dispersion power). The main adjacent source of pollen deposition is provided by Gramineae and Compositae. Other pollen types have low or very low dispersion power, among them the characteristic páramo herbs. Polylepis sericea, a tree which grows high above the common tree line, has very low pollen dispersion power, and low pollen deposition; its presence can be detected only if the trees grow near the deposition site.

ISSN:0017-3134    

DOI:10.1080/00173137909428871

出版商:Taylor & Francis Group    

年代:1979

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:10.1080/00173137909428863

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor