摘要:

The colony ofErica vagansin County Fermanagh, Northern Ireland was surveyed and soil and species‐association analyses were carried out. The species is found in a base‐rich flush, were it survives due to reduced competition from calcifuge species and is associated with other species that tolerate the relatively calcareous environment. The colony is uniquely uniform in flower colour and does not appear to be able to reproduce sexually at this time. The species probably arrived in Ireland in postglacial times and has since becomegeneticallydistinct.fi.vagansdoes not appear to be a recent introduction, though man may have been involved in determining its present distribution and that of the other so‐called “Hiberno‐Lusitanian”Ericaceae. While considerable doubt remains concerning the origin and age of the colony, the species cannot be regarde

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1974.tb01624.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

The Loma Mountains (2090 m), situated in lowland south Guinea savanna in Sierra Leone, are shown to have a cooler and more mesic climate than the savanna region. A temperature lapse rate of 7.5oC/1000 m is calculated using means for the dry, dry/wet, wet and wet/dry seasons of the year. In the montane grassland the life forms of the species are predominantly hemicryptophytic, and the biological spectrum is closer to that of temperate grasslands than to the savanna type, although the adverse conditions are still dry‐season drought and fires. The phytogeographical distribution of the flora indicates a 44% widespread, truly montane to montane/savanna element and a 43% West African endemic element. In the Guinean highlands, the Loma/Tingi group shows about 10% disjunction of its grassland flora with other African mountains outside West Afric

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1974.tb01625.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

Certain developmental and anatomical studies onD. sansibarensisPax are briefly reported. (1) Stem diameter, internodal length, vessel diameter, distribution and number of vascular bundles in internodes (from base to apex) are determined. There is no correlation between vessel size and stem diameter. Cut stems left in water develop tyloses. (2) Roots are all polyarch. The development and structure of the vessels are discussed. Xylem and phloem differentiation in the root tip is determined. A central meristem at the root apex gives rise to the different tissues in the root. Raphide development in root cortex is traced. (3) Both alternate and opposite leaf arrangements occur, sometimes on the same plant, and there is a correlation between stem thickness and leaf arrangement. During leaf development the lamina length exceeds the width, but the two dimensions reach their maximum size at the same time. The acuminate leaf‐tip matures before the rest of the leaf. Stomatal development is trace

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1974.tb01626.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

The Brazilian seaweeds studied by G. Dickie (1874) have been critically reviewed and several names corrected according to new taxonomic concepts. Some doubtful records have been indicated.

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1974.tb01627.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY