摘要:

Twenty‐nine populations of three closely related taxa,Asplenium lepidum, A. haussknecktiiandA. samarkandense, have been raised together in cultivation. There is considerable inter‐population variation, and the ranges of variation of the three species overlap. Cytogenetic investigation of artificial hybrids has shown that the three taxa are all allotetraploid and that they share the same diploid parents,A. aegaeumandA. ruta‐murariasubsp.dolomiticum.Analysis of F1 and F2 hybrids between different populations indicates high inter‐fertility.The aggregate is re‐defined as a single polymorphic species(A. lepidum)consisting of two subspecies (subsp.lepidumand subsp.haussknechtii)distinguished primarily by gland and sporangial characters.A. samarkandenseis reduced to a variety of subsp.haussknechtii.It is suggested that the two subspecies have had separate geographical origins from different morphological variants of the same diploid parents, but the polymorphic nature of the aggregate is principally due to divergent evolution in small populations isolated on limestone mountains in southern Europe and wes

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1976.tb01363.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

A review of the pteridophytes of Rodrigues and their ecology is presented, based on a brief survey in 1973 and earlier records. Twenty‐five species are listed, two of theSelaginellaspecies being endemic. Three additional species have been recorded as native or naturalized:Lycopodium cernuum, Ophioglossum pendulumandSalvinia molesta.Four species not recorded since 1879 are presumed extinct. Nature reserves are needed to preserve the remnants of native plant communitie

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1976.tb01364.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

Plants ofD. sansibarensisPax bear opposite or alternate leaves, very rarely both on the same plant. The shoot apex shows distinct histological zonations irrespective of the phyllotactic variation. Three or more buds are produced in almost every axil, starting from the third node. The largest (axillary) bud is nearest the stem and always develops into a lateral branch. The 2–4 accessory buds develop conjunctly into a bulbil. Bulbil growth is traced and allometric relationships are shown to exist between the different parts of the bulbils. Histogenesis and organogenesis in bulbils are explaine

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1976.tb01365.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

Developmental studies of stomata in the tribes Cymbidieae, Maxillarieae and Gongoreae (Orchidaceae) demonstrate the presence of definite subsidiary cells in these groups of the Orchidaceae, contrary to recent reports that the Orchidaceae lack subsidiary cells. Fifteen species in these groups were studied developmentally and an additional 36 species were studied from mature leaves. In the Cymbidieae the subsidiary cells may be the lateral trapezoid cells derived from the lateral contact cells, or the subsidiary cells may be derivatives of the trapezoid cells. In the species of Maxillarieae and Gongoreae studied the subsidiary cells were derivatives of the trapezoid cells. The type of subsidiary cell development in these groups is essentially the same as has been found in other advanced groups of epidendroid orchids that have subsidiary cells.

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1976.tb01366.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

Continued botanical exploration in northern South America has yielded material necessitating description of two new taxa ofNiphogetonand revision of the descriptions of two others; illustrations supplement the descriptions. A new key to the species of the genus as now augmented is offered to replace that published 25 years ago. The taxonomic implications for this genus of Cerceau‐Larrival's studies of seedlings and pollen of Umbelliferae are discusse

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1976.tb01367.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY