摘要:

Quantitative and qualitative data are presented for 11 collections of six species. The wide range of character states for the species is presented in the form of a key to emphasize their potential systematic correlations. Distinctive among these are phcllem characteristics. Fibre‐tracheids are newly reported for lianoidGnetumspecies. Cells previously thought to be like companion cells in secondary phloem are shown to be uniseriate rays, counterparts to uniseriate xylem rays. Laticifers are abundant in most of the species, and are newly described for secondary tissues ofGnetum.Presence of tyloses in laticifers of two species is apparently a new report for vascular plants. Tori are present in two New WorldGnetumspecies, adding to the report in African species. Perforation plates are simple except near or in primary xylem, where they are simple or foraminate. Torus presence and foraminate perforation plate presence are features more reminiscent ofEphedraand other gymnosperms than of angiosperms. The bark ofGnetumis also very similar to that ofEphedr

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1996.tb00476.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

The circumscription of the two Arabian speciesSarcostemma forskaolianumSchult. andS. vanlesseniiLavranos is clarified.S. vanlesseniiis identified as a widespread species, occurring in East Africa and the southern Arabian Peninsula. Within theSarcostemma viminalecomplex, three new subspecies are delimitated. Subspeciesodonlolepis(Balf.f.) Meve&Liede, comb, et stat. nov. is established for glabrous, strongly twinning plants close to those of subspeciesbrunonianum(Wight&Am.) P.I. Forst., but distinguished by flower‐bearing laterals and an outer corona half as high as the gynostegium. Ecologically, this taxon is confined to coastal habitats in East Africa. Subspeciesstipilaceum(Forssk.) Meve&Liede, comb, ct stat. nov. covers stout, non‐twining representatives of East Africa and Arabia, also with short flower‐bearing laterals. SubspeciessuberosumMeve&Liede, subsp. nov. is newly described to accommodate the most frequent East African form ofS. viminale, often mistaken for the typical subspecies. All taxa are described in detail, chromosome numbers are given and distribution maps are provided forS. forskaolianum, S. vanlesseniiandS. viminalesubsp.odontolepis.A synopsis of all taxa occurring in East Africa and Arabia and additional chromosome numbers are pro

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1996.tb00477.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

The British elms have historically proven to be recalcitrant taxonomically, with at least six different levels of treatment being applied. The taxonomic history of“the group and the nomenclature is outlined from the ancient authors up until the present day. This paper is the foundation for future articles in which a novel taxonomic treatment is introduce

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1996.tb00478.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Similar karyotypes ofIn =22 inCycas circinalis, C. mediavar.basaltica, C. revoluiavar.rewluta, C. revolutavar.taiwanianaandC. siammsiswere compared with each other by using the CMA and DAPI fluorescent staining methods. Their four largest submedian‐centromeric chromosomes each had a CMA band at the terminal region in common. Their 12 terminal‐centromeric chromosomes commonly displayed CMA bands at the terminal region and the pericentric region. Two of the 12 terminal‐centromeric chromosomes carried a CMA band somewhere in the interstitial region of the long arm.C. circinalisalone showed it at a relative position closer to the centromere. The other taxa showed it at a relative position near the terminal region. All of the chromosomes exhibited the DAPI dot at the centromeric r

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1996.tb00479.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Phylogenetic relationships between the European species of the genusGentianaL. (Gentianaceae) were inferred from chloroplasttrnL, (UAA) intron sequence data. The phylogeny obtained is largely in accordance with the classification of species into sectionsGentiana, MegalantheandCalathianae.Few synapomorphies support the branching of the main lineages and thus could suggest a rapid radiation following the colonization of Europe. Within sectionGentiana, our results are highly congruent with the previous distinction ofG. montserratiiVivant fromG. luteaL. SectionMegalantheis divided into two well separated lineages, both of which comprise calcicole and calcifuge species. The ‘star phylogeny’ obtained in sectionCalathianaesuggests that most of the taxa speciated almost simultaneously. Relative‐rate tests between two lineages suggested that sectionChondropliyllaedisplays higher mutation rates than the rest of the genusGentianaand that cpDNA can violate assumptions of rate constancy at lower taxonomic

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1996.tb00480.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

The cycad%amia loddigesiiMiq. forms a morphologically variable complex on the Yucatan peninsula, Mexico. Several diploid chromosome numbers have been found in the species:In= 17, 24, 25, 26 and 27. Differing karyotypes and chromosome numbers were found in individuals of the same population and die karyotypes differ widely in numbers of metacentric and telocentric chromosomes present. Centrometric fission as well as pericentric inversions and unequal translocations are suggested to betheprobable mechanisms for this karyotype variation. There appears to be a correlation between high chromosome number and increasing dryness of the habitats. Coupled with the strongly asymmetrical karyotypes, this suggests that karyotype evolution inZ‐ loddigesiiis recen

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1996.tb00481.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Book reviewed in this article:Plant Stems. Physiology and Functional Morphology, ed Gartner, Barbara L. Academic Press, UK.Terrestrial orchids from seed to mycotrophic plant, by Rasmussen, Hanne. Cambridge University Press, Cambridge, UKThe Electronic Comparative Plant Ecology, by J. J. Hodgson, J. P. Grime, R. Hunt and K. Thompson. Chapman and HallA Monograph of Didymosphaeria, by Andre Aptroot.The Manuleae. A Tribe of Scrophulariaceae, by Olive M. Hilliard.

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1996.tb00482.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1996.tb00476a.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY