摘要:

In Caliciales both passive and active spore dispersal occurs. A review of the distribution of 162 species is given. Species with small spores have wider distribution than species with large spores, irrespective of dispersal strategy. In antitropical species there is only rarely a differentiation between Northern and Southern Hemisphere populations. It is concluded that in several small‐spored genera long‐distance dispersal has been instrumental in dispersing the species and range extensions have been much more frequent than in large‐spored species for which vicariance explanations are more appropriate. Comparisons with bryophyte distributions show differences in dispersal strategies and distribution pat

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1994.tb00429.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Quantitative and qualitative data are presented for seven collections representing two varieties (unlike in habit) ofGnetum gnemon.Tracheids are present, but abundant and intermixed with them are septate fibre‐tracheids rich in starch. Axial parenchyma has been reported only once previously for the species. Axial parenchyma is in strands of 4–10 cells, is rich in starch, is primarily vasicentric (paratracheal) in distribution, less commonly diffuse. About equally common are simple and compound perforation plates; the latter are composed of from two to about ten bordered foraminate perforations, the shape of which may be altered by crowding or coalescence, but is clearly still foraminate. Lateral walls of vessels bear pits that are vestured around pit cavities, not facing the pit membrane. Rays are composed mostly of procumbent cells; the tangential walls bear bordered pits. Crystals, present in ray cells and (rarely) axial parenchyma vary widely in size. Crystalliferous sclereids with layered walls, starch‐rich parenchyma, and gelatinous secondary phloem fibres are the main components of bark. Early stages in origin of successive vascular cambia in bark are newly described. When representative conditions are derived from study of large numbers of slides, the classical view thatGnetumvessels are unlike those of angiosperms is supported. Features ofGnetum gnemonwood are discussed in the light of ecology and conductive physi

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1994.tb00430.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Phenology and anatomy of the reproductive phase ofAbies pinsapowere studied. Male cones and female cones were differentiated in the autumn, and the dormant microsporangia contained pollen mother cells (PMCs) in the premeiotic stage. The male cones broke dormancy at the end of February when the pollen mother cells began meiosis. Pollen grains were shed at the five‐celled stage at the end of April‐early May. The female cones broke dormancy in mid‐April. Anthesis took place at the end of April. No micropylar‐pollination droplet was observed. After pollination the female cones developed quickly. The most important loss of cones occurred during the pollination period. The number of archegonia varied from one to three but two was most common. Fertilization took place at the end of June. The embryos developed during the summer, and seeds were dispersed in autumn. The results are discussed in relation to other c

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1994.tb00431.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

The subterranean, monopodial caudex ofRhodiola roseahas unilacunar, two‐trace nodes, whereas its annual leafy flowering shoots have the more common unilacunar, one‐trace nodes. The double‐traced unilacunar nodal structure of the highly specialized caudex is considered to be the advanced condition in this species as well as in the Crassulaceae in general. The character may be significant in evolutionary and systematics studies of the genusRho

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1994.tb00432.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Book reviewed in this article:Australian Tropical Rain Forest Trees, An Interactive Identification System, by Hyland, BPM and WhiffenThe Rainforest Edge, edited by John HemmingAtlas of the Bryophytes of Britain and Ireland. Volume 3. Mosses (Diplolepideae). Hill, M. O., Preston, C. D.&Smith, A. J. E.Phytochemistry and Agriculture, Beek, van T. A. and Breteler, H. Proc.Manual of Vascular Plants of Northeastern United States and Adjacent Canada. Second Edition. by Gleason, H. A.Flora of Flintshire by Goronwy WynneUltrastructure of Fossil Spores and Pollen, edited by Kurmann, M. H. and Doyle, J. A.

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1994.tb00433.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY