摘要:

Karyotype morphology ofPsophocarpus tetragonolobusandP. scandensis described and the behaviour of chromosomes at meiosis discussed. Both species have a chromosome number of2n =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 thatP. scandenscannot be the immediate wild ancestor of domesticatedP. tetragonolobus. Study of meiotic chromosomes and analysis of qualitative and quantitative variation in Papua New GuineanP. tetragonolobussuggest that there are few restrictions to recombination other than those imposed by predominant self‐pollination, The bearing of these data on the taxonomic relationships ofPsophocarpusand on chromosomal evolution within the Phaseolinae is discusse

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1980.tb01665.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

Twelve previously described shrubby species ofAloéL. from Kenya, Congo, Tanzania and Uganda were investigated using a multidisciplinary. approach. Half of the species were found to be tetraploids (24, 28), and because of the rarity ot tetrapolody in the genus it is suggested that these are very closely related and of common origin. Studies of their gross morphology and leaf surface sculpturing reveal clinical variation patterns. These patterns indicate the diploid species likely to be similar to the ancestor of the tetraploids, and the geographic region where the chromosome doubling probably occurred. Variations in the composition of the leaf exudates largely confirm the conclusions drawn from the cytological and anatomical observations. A taxonomic revision based on the experimental findings changes the status of Rift Valley forms ofA. kedongensisto a subspecies ofA. nyeriensisand also enlarges the latter to includeA. ngobitensis

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1980.tb01666.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

The leaf anatomy of the subtribe Hyptidinae (Labiatae), which consists of four small genera and the largr genusHyplis, is dercribed. The leaves may be dorsiventral or isobilateral. Variable characters of the lainina include: frequency and forms of trichomes, cuticular markings, presence of adaxial stoinata, thickness of leaf, thickness of adaxial epidermis, presence of a hypodermis, occurrence of sclcrified tissues (especially sclerified bundle sheath extensions, phloem and xylem fibres), mesophyll structure and venation pattern. Petiole vasculature varies from simple to complex, sometimes with medullary traces present. Most of the variable characters are related to xeromorphy and are tax‐onomically useful within the framework of the present classificatio

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1980.tb01667.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

Most Helonieae have only slight septal indentations between the three carpels: inXerophyllumdeep septal clefts extend centripetally and completely enclosed, narrow septal pockets occur inMetanarthecium. Other unique generic features are found: tepallary‐staminal nectarial glands inHeloniopsis, zygomorphy inChionographis, and dioecism inChamaelirium. The carpels are biovulate inChionographis;there are two to several ovules per carpel inXerophyllum;8–12 ovules occur in the carpel ofChamaelirium;and numerous bitegmic ovules are borne in many longitudinal rows on enlarged placentae inHelonias, Heloniopsis, Metanarthecium, andYpsilandra. Except forMetanarthecium, this last‐named group of genera displays a near ring composed of ‘accessory’ placental bundles and a compound septal bundle (with normally oriented xylem and phloem) in cross‐section at the inner edge of each septum. Ventral bundles occur in the other

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1980.tb01668.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

Eighty‐eight species of West African orchids were examined for tratheoidal elements in the root, stem, pseudobulb and leaf. Forty‐three species (49%) contained tiacheoidal elements. al were epiphytic species; none of the twelve terrestrial and one epilithic/terrestrial species examined contained tracheoidal elements. Of the epiphytic species, twenty‐one contained tracheoidal elements in the roots; seventeen in the stem/pseudobulb and twenty‐three in the leaves.The tracheoidal elements are similar in structure: they all possess annular, spiral, reticulate or pitted secondary wall thickenings. These elements vary in shape, size and distribution in the different species and these variations may be of some taxonomic use within the Orchidaceae.The functions of the tracheoidal elements is not clear, but they probably provide mechanical support and also aid water ‐retention in the organs contai

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1980.tb01669.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

A specimen collected in southern Tibet in 1928, hitherto identified only as“Arenanusp.”, is found to represent a new species of the subgenusOdontostemma. The new species resemblesA. littledalei, the species that forms the basis of the monotypic genusGooringia, characterized by a dwarf habit, a tetramerous perianth and only two or three stamens. Several other species ofArenariasubgenusOdontostemmaresembleA. littledaleiin habit and one (A. saginoides) is tetramerous, but hitherto none has been found with its extremely reduced androecium. The new species has an identical androecium toA. littledaleiand its discovery leaves no doubt thatGooringiashould not be recognized taxonomically at any rank. The new species is described asA. pharensisMcNcill&Majumdar and a table compares its diagnostic features with those ofA. littledaleiand five other dwarfArenariaspecies of sibgrnusOdontostemmafrom the mountains of Sikkim, Tibet, Yunnan and Tsing

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1980.tb01670.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY