Study of electrophoretic variability in Epipactis helleborine (L.) Crantz,E. palustris (L.) Crantz and E. microphylla (Ehrh.) Swartz (fam. Orchidaceae)

Allozymic variation in seven enzymes coded by eight loci was studied in seven populations of terrestrial Epipactis orchids, including four populations of E. helleborine, one population of E. palustris and two of E. microphylla, from Latium (Central Italy).Heterozygosity estimates reveal that E. helleborine (EH) is the most variable species (HET=0.233; P=0.59; A=1.8), followed by E. palustris (EP) (HET=0.085; P=0.29; A=1.3) while E. microphylla (EM) is monomorphic for all the loci examined.It is suggested that the two EM populations examined, with a total lack of genetic variability, could originate from the same genetically impoverished ancestral population. Also the low variability amount of EP can be ascribed to genetic drift, probably due to a founder event.Nei's identity coefficients were also calculated. These show a high similarity in EH (=0.987) and EM (=1.000) populations. Average identity value between EP and EM is 0.289, between EP and EH is 0.336 and between EM and EH is 0.784. These data reveal that E. palustris presents a remarkable genetic, besides geographical and ecological, differentiation.     

Cytology of two species of winged bean, Psophocarpus tetragonolobus (L.) DC. and P. scandens (Endl.) Verde. (Leguminosae)

Karyotype morphology of Psophocarpus tetragonolobus and P. scandens is described and the behaviour of chromosomes at meiosis discussed. Both species have a chromosome number of 2n = 18 and similar karyotypes of a sort unusual within the Phaseolinae. Differences between the species in detailed morphology of the chromosomes agree with data from external morphology, palynology and crossability in indicating that P. scandens cannot be the immediate wild ancestor of domesticated P. tetragonolobus . Study of meiotic chromosomes and analysis of qualitative and quantitative variation in Papua New Guinean P. tetragonolobus suggest that there are few restrictions to recombination other than those imposed by predominant self-pollination, The bearing of these data on the taxonomic relationships of Psophocarpus and on chromosomal evolution within the Phaseolinae is discussed.     

Patterns of provisioning and iteroparity in a solitary halictine bee,Lasioglossum (Evylaeus) fratellum (Perez), with notes onL. (E.) calceatum (Scop.) andL. (E.) villosulum (K.)

Summary On Dartmoor, UK the temperate halictine beeLasioglossum (Evylaeus) fratellum is solitary and univoltine. A significant proportion of individually marked foundresses reproduce during two different seasons (iteroparity). This could represent a form of risk-spreading in environments where conditions are harsh and unpredictable. Perhaps associated with iteroparity, foundresses put in relatively low reproductive effort, often failing to provision their nests on suitable days, despite the small number of days available on Dartmoor. Foundresses stopped provisioning asynchronously, then remained in their nests until well after offspring emergence. There was a small proportion of digynous nests, in which nest-sharing appeared to be temporary.L. (E.) calceatum had a similar life-cycle on Dartmoor.L. villosulum was also solitary, and was able to provision its nests under less favourable weather conditions than the other two species. Information is also provided on nest productivity andSphecodes parasites.     

中国绢蒿属志——中国绢篙属植物的系统分类、分布和主要经济用途

本文详述了中国绢蒿属植物的系统分类、分布和主要经济用途.     

l-Arginine and l-Canavanine Metabolism in Jack Bean, Canavalia ensiformis (L.) DC. and Soybean, Glycine max (L.) Merr

Studies have been conducted with the arginase (l-arginine amidinohydrolase, EC 3.5.3.1) of two legumes: jack bean, Canavalia ensiformis (L.) DC., a l-canavanine-containing plant and soybean, Glycine max, a canavanine-free species. Analyses of the arginase obtained from gradient-purified mitochondria of these legumes revealed that the arginine-dependent (ADA) and canavanine-dependent activities (CDA) were localized within this organelle.     

Taxonomic notes on Cheilothela (Lindb.) Broth. and Dicranella (C. Muell.) Schimp.

Abstract

The widespread occurrence of a number of bryophytes on British saltmarshes is reported. The communities in which bryophytes are most frequently found are discussed. These communities are more common on marshes on the west coast of Britain. Differences between moss assemblages on salt marshes in England and Wales and in Scotland are emphasised and the greater range of habitat preference demonstrated by Grimmia maritima in Scotland is commented upon.     

A comparison of Dichodontium flavescens (Dicks.) Lindb. and D. pellucidum (Hedw.) Lindb. (Bryopsida)

Abstract

Fifty-three herbarium samples of the genus Dichodontium, originating from 15 countries in Europe and North America, were examined to critically assess new distinguishing characters between D. flavescens and D. pellucidum. The examination, including SEM, revealed some new characteristics in the gametophyte, notably leaf shape, leaf length: width ratio, and width of the nerve, permitting accurate determinations even on sterile material. D. flavescens is recognized here as a distinct species.