ISSN:0017-3134    

DOI:10.1080/00173137209429870

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

Reproductive organs ofAzollaspecies (Salviniaceae) from the Lower and Middle Pleistocene of the Dansk Nordsø A-1 and A-2 boreholes, central North Sea area, were studied by means of scanning electron microscopy. A new species,Azolla danica,based on massulae is proposed. The megaspore apparatuses ofAzolla filiculoidesLam. andAzolla tegeliensisFlorschütz are described and the possible affinity ofA. danicatoA. tegeliensisis discussed. It is concluded, that theA. danicamassulae can be regarded as the previously unknown massulae ofA. tegeliensis.A tentative, chronostratigraphical subdivision of the Quaternary section is given. The record ofA. tegeliensisis the first proof of the presence of limnic deposits of the Tiglian interglacial within Danish territory.

ISSN:0017-3134    

DOI:10.1080/00173137209429871

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

Pollen of seven genera was introduced into a stream originating from a mountain glacier in Yosemite National Park, California, USA. Cold nights and warm days produced a daily cycle of low and relatively still water followed by vigorous flow. During the ensuing 16 days repeated samples were taken of bottom sediments in stream pools and ponds from 25 sites ranging from control sites above the release point to 23 km downstream. Introduced grains were recovered from experimental and control sites within 3 km of the release point; data from these sites are presented in detail. Within the limits of the experiment there was no evidence for the segregation of pollen and spore types either in space or with time. Several days after its introduction in the stream the exotic pollen could be recovered from ponds having no water connection with the stream and also higher in elevation than the point of release of foreign pollen. Apparently the pollen became airborne, perhaps after being stranded at the water's edge or, more directly, released from the film of water surrounding air bubbles. If this should be a common phenomenon, then the entry of long-distance pollen into sediments by local air transport of grains released from rivers offers interpretive possibilities, since the direction of pollen transport in the stream would be independent of wind direction.

ISSN:0017-3134    

DOI:10.1080/00173137209429872

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

High resolution autoradiography has been used to study synthesis and localization of chloroplast DNA after incorporation of H3-thymidine into germinating spores ofEquisetum fluviatilevar.verticillatum(Døll). Enzymatic and acid hydrolysis of the material with DNase, RNase, TCA and PCA, showed that almost all the incorporated radioactivity was associated with the DNA in the chloroplasts, mitochondria and nuclei. The chloroplast DNA was presumably synthesizedin situ,since no direct relationship to the nuclear DNA transcription process could be found. Semiquantitative studies revealed no increase in the incorporation of tritiated thymidine into the DNA of the spore cells when the concentration of tritium labelled thymidine in the growth medium was doubled. This finding may have alternative explanations; either the exogenous thymidine in high concentrations totally blocks the normal thymidine synthesis pathway; or the limited uptake of thymidine from the medium may signify a fixed pool of exogenous thymidine in the cells. On the autoradiographs, the silver grains which overlay the chloroplast of the sectioned material, were with few exceptions randomly distributed.

ISSN:0017-3134    

DOI:10.1080/00173137209429873

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

The pollen morphology of the following genera is described:Manglietia(1 sp.),Magnolia(10 spp.),Talauma(2 spp.),Alcimandra(1 sp.),Michelia(5 spp.) andLiriodendron(2 spp.). It is shown that from a pollen morphological point of view the Magnoliaceae are a homogeneous, natural group.

ISSN:0017-3134    

DOI:10.1080/00173137209429874

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

Scanning electron microscopy was used to examine the wall sculpturing of pollen fromZea maysL. ssp.mays(maize),Zea maysssp.mexicana(Schrad.) Iltis (teosinte),Zea perennis(Hitchc.) Reeves and Mangelsdorf (perennial teosinte), and two species ofTripsacumL. TheZeataxa are shown to possess similar pollen types, with spinules scattered regularly over the exine surface.Tripsacumexhibits a distinctly reticuloid pattern, with spinules clumped into isolated lacunae. Hybrids betweenZeaandTripsacumare either intermediate in exine pattern or similar toTripsacum,depending on the genome combination.

ISSN:0017-3134    

DOI:10.1080/00173137209429875

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

G. Thanikaimoni: Index Bibliographique sur la Morphologie des Pollens d'Angiospermes. — Institut Français de Pondichéry Travaux de la Section Scientifique et Technique, Tome XII, Fascicule 1, French Institute, Pondichéry, 1972 (339 pp.), 50 FF (with English preface). Reviewed by J. R. Rowley.

ISSN:0017-3134    

DOI:10.1080/00173137209429876

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

ISSN:0017-3134    

DOI:10.1080/00173137209429877

出版商:Taylor & Francis Group    

年代:1972

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:10.1080/00173137209429869

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor