摘要:

Cytological observations on eleven species ofOphioglossumrevealed low gametic (n) chromosome numbers of 30, 34 and 60 in populations ofO.eliminatum, contrasting with an earlier report ofn= 90 in the same species. The rest of the species is based onn=120.Cytologically studied species ofOphioglossumexhibit a range of chromosome numbers from n = 30 inO.eliminatumton=720 inO.reticulatum.The weighted highest common factor (HGF) from all the reported chromosome numbers in twelve species was found to be 30. This number is proposed as the palaeobasic chromosome number for the genuS. Reported chromosome numbers which are not multiples of 30 were subjected to sequential analysis, yielding three distinct ultimate base numbers, 4, 5 and 6, which can producen= 30 in seven different ways. The neobasic number,n=120, appears to have arisen through various combinations and permutations of these, theoretically 2401 routes; only a relatively few of these routes exist today, suggesting that extreme selection has been exerted against the majority, and further suggesting thatOphioglossumrepresents an evolutionary dead end through repeated cycles of polyploidy and is possibly at the verge of extinction. The stoichiometric model of evolution, which derives the various chromosome numbers possessed by the twelve species from the basic and ultimate basic chromosome numbers, is used to explain chromosomal evolution in the genus.

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1990.tb01876.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

This genus introduces the trichasium into the morphology of fagaceous inflorescenceS. Other genera of the family are considered to have been derived from ancestral pachycaulTrigonobalanuswith large whorled leaves and ever‐suckering habit, perhaps originally monocarpic. The genus is regarded as a tropical problem of the west Pacifi

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1990.tb01877.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Pericarp structure is surveyed in 29 genera. Homologous regions termed exocarp, mesocarp and endocarp are established. While exocarp and mesocarp structure show some uniformity, there are two very distinct types of endocarp, designated theAnacardium‐type and theSpondias‐type.The distribution of these indicates that the current division of the family into five tribes is artificial. The occurrence of theSpondias‐typeinCanarium, a member of the sister group Burseraceae, suggests that this type is plesiomorphic in the Anacardiaceae. In addition, the presence of theAnacardium‐type inBlepharocarya(Blepharocaryaceae) andOrthopterygiumQulianiaceae) further supports the inclusion of these taxa in the Anacar

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1990.tb01878.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Material ofSolanumsectionSolanumfrom India and Pakistan is assignable to three species: a diploid,S. americanum;a tetraploid,S. villosum;and a hexaploid,S. nigrum.These species are distinguished by slight but consistent differences and a key is included to facilitate their identification. None of the members of sectionSolanumappears to be a weed of significant agronomic importance in this area, except in a few localized areas.

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1990.tb01879.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

The karyological survey of the Spanish taxa of Lithospermeae is completed with studies ofOnosmaL., CerintheL. AndAlkannaTausch. The chromosome number ofO. TricerospermaLag.subsp.tricerospermais reported for the first time and those ofC.gymnandraGasparr. AndA. Tinctoria(L.) Tausch have been counted for the first time in Spanish material.Con este trabajo se completa el estudio cariologico de los taxones espanoles de Lithospermeae. Se estudian los correspondientes aOnosmaL., CerintheL.yAlkannaTausch, de ellos, el niimero cromosomico de0. TricerospermaLag.subsp.tricerospermase indica por primera vez y los deC.gymnandraGasparr.yA. Tinctoria(L.) Tausch corresponden al primer recuento con material espanol.

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1990.tb01880.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

As an aid to taxonomic discussions, patterns of leaf exudate compounds separated by two‐dimensional thin‐layer chromatography and revealed by staining with Fast Blue B have been obtained for all but one of theAloespecies in Reynolds' Group 19 and SeriesArborescentes.Plants in these two subdivisions of the genus are linked by their affinity toA. Arborescens, a widespread species which occurs in both groupings. Three types of compounds can be distinguished by their staining reactions and u.v.fluorescence, the anthrone C‐glycosides (yellow, green, blue, grey to brown colour reaction), the chromones (orange colour reaction) and a large mixed group of phenolic compounds, including phenylpyrones (staining various shades of purple).On the basis of patterns containing these chromatographic zones, the shrubby aloes were divided into four arbitary divisions although at this stage no taxonomic implications are claimed, the classification being purely chemical and reflecting differences in their biosynthetic constitution. One species,A.pluridenswas peculiar in having an exudate with none of the staining compounds present, although the supposedly secretory ‘aloin’ cells were prominent in the leaveS. Determination of the partition coefficients of the three main anthrone C‐glycosides demonstrates that homonataloin is more lipophilic than barbaloin and might be expected to accumulate in more hydrophobic regions

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1990.tb01881.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Previous classification of the Disinae has been based almost entirely on floral morphological data. These data are critically assessed by various methods to determine to what extent they support a classification resolved to sectional level. The variation in the characters relative to the sections and genera is mapped, homologies are established by careful morphological observation and ontogenetic studies, and finally hypotheses of homology are tested by congruence in several cladistic analyseS. It is found that although floral morphology allows the recognition of some groups, for others the results are ambiguouS. Floral morphological data are clearly inadequate to establish the taxonomy of the Disinae on a sound footing.

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1990.tb01882.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY