摘要:

Flowering and fruiting behaviour of female and hermaphrodite florets is described and assessed in samples from three populations from Denmark, England and Sweden. Between 25 and 50% of the florets in capitula are female, and flowering gender varies little among plants in each population. Fruiting gender of individuals,G(femaleness), varies from 0 to 0.85, because of variation in fruit set and fruit abortion. Variation in fruiting gender was correlated with plant size parameters in two populations, but not in the third. The data suggest that post‐anthesis regulation of maternal investment may be operating. Florets ofA. vulgarisare either totally specialized for pollen receipt (female florets) or largely specialized for pollen donation (hermaphrodite florets), and show adaptations for avoiding interference with each other in these functions. Movement of capitula from a pendent position at flowering to an erect position at fruiting optimizes positions for dissemination of pollen and of seeds respectivel

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1986.tb01433.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

The development and structure of the exo‐, meso‐ and endocarp of the drupe ofSclerocarya birreasubsp.caffrawere examined. The mature exocarp comprises the outer epidermis with stomata and lenticels, subepidermal collenchyma and parenchymatous layers with secretory canals. This exocarpsensu latodevelops from the outer epidermis and the outer layers of the ovary wall. The fleshy parenchymatous mesocarp or sarcocarp also contains secretory tissue. The mesocarp develops after endocarp differentiation and lignification. The developmental sequence within the pericarp corresponds to the general pattern in drupes. The endocarp or sclerocarp, which is not stratified, consisting mainly of brachysclereids, fibres and vascular elements, develops from the inner epidermis and adjacent tissue of the young ovary wall including the procambium strands. The operculum represents a well‐defined part of the endocarp. Early in its development a parenchymatous zone already clearly demarcates the operculum. The literature on the pericarp of the Anacardiaceae drupe is discussed to establish the diagnostic value of these morphological characteristics for future taxonomic st

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1986.tb01434.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Shoots of adult plants ofLilaea scilloideshave a sympodial form. Each unit of the sympodium bears a single sheathing prophyll (which is the only kind of foliage leaf produced in the adult) and terminates in an inflorescence. The prophyll subtends the next unit of the sympodium. A further accessory bud can form in association with each unit. This bud repeats the pattern of the main sympodium, giving the plant a tufted habit. Five different kinds of flower can be identified in the inflorescence: a unisexual male flower with a single perianth member and adnate stamen; a bisexual flower, with a single perianth member and adnate stamen, and a single carpel with an anatropous bitegmic ovule; a unisexual female flower with a single perianth member and carpel; a unisexual female flower comprising only a single carpel; and a female flower comprising only a single carpel with a very long filamentous style. The first four kinds occur in the upper part of the inflorescence which is normally elevated on a scape, while the last kind is restricted to the base of the inflorescence. In the position of the basal flowers several variations have been observed in cultivated material. These include branching associated with the basal flowers, which results in the development of additional basal flowers or inflorescences, and even total replacement of a basal flower by an inflorescence or a branching structure bearing flowers. A review of past literature includes a clarification of some persistent errors which have confused the taxonomic position of the plant and the morphological interpretation of the reproductive appendages.

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1986.tb01435.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

A brief historical background is provided concerning some early collectors and their pteridophyte collections in South Africa which preceded the publication of Kunze'sAcotyledonearum Africae Australioris Recensio Nova, a paper which was largely based on the pteridophyta collection of Drege, Ecklon and Zeyher. This paper was reprinted twice during 1836. Inconsistencies led to a great deal of confusion. Kunze recognized a total of 123 species (a figure which excluded forms and varieties), and of these 29 were described for the first time. The destruction of Kunze's herbarium resulted in most of his species which are described here, and elsewhere, remaining untypified. A search in most of the prominent European herbaria has revealed that adequate duplicates still exist and most of the taxa described by Kunze in the relevant publication can now be typified.

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1986.tb01436.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Compounds in the leaf exudates of a group of shrubby aloes from East Africa have been re‐examined by two‐dimensional thin‐layer chromatography using Fast Blue B as a revealing reagent. Exudates from the most abundant taxa, the two subspecies ofAloe nyeriensis, were found to contain substances giving four distinct chromatographic patterns. One was distinguished by the presence of the anthrone C‐glycoside barbaloin while two others contained instead homonataloin with or without aloenin. The fourth group contained neither of these but a similar compound of unknown constitution. Exudate patterns from the neighbouring but localized tetraploid speciesA. cheranganiensis, the more remoteA. daweiandA. elonica, together with the diploidA. yavellana, related to one or other of the groupings ofA. nyeriensis.Some plants of a localized diploid species,A. morijensis, also yielded a similar pattern but other plants of rather more slender form contained quite different compounds resembling those in the diploidsA. fibrosaandA. babatiensis.This supports the hypothesis thatA. morijensisis close to the putative ancestor of the tetraploid East African shrubby aloes. The other widespread shrubby species in this locality, the diploidA. rabaiensis, is unrelated taxonomically and che

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1986.tb01437.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Compounds in the leaf exudates from 43 individuals ofA. elgonicacollected on Mount Elgon on the Kenya‐Uganda border and raised at Kew were examined by two‐dimensional thin‐layer chromatography. The compounds reacting with Fast Blue B to give coloured zones showed patterns of variation throughout the species. These patterns could not be correlated with the considerable variations in chromosome form and leaf surface anatomy. The two major compounds in the leaf exudates were the anthrone C‐glycosides, barbaloin and homonataloin, which were never observed together in the same plant. Aloenin occurs throughout the species in every plant examined, varying only in amount as detected by s

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1986.tb01438.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Examination ofAloeleaf sections revealed the presence of three types of cells at the phloem pole of the vascular bundles, aloin cells, outer bundle sheath cells and fibres. Three species contain fibres alone and produce a sparse exudate with few components staining purple with Fast Blue B on thin‐layer chromatograms. The majority of species have aloin cells of various sizes and in the tetraploid species these produce a copious exudate containing anthraquinone and chromone derivatives. It is suggested that the aloin cells act as storage tissue and that the compounds are synthesized in the surrounding layer of cells of smaller diameter, many of which can be seen to contain globules of unknown constitution. Anatomical observations support the idea that the shrubby tetraploidAloespecies are derived from a form similar to the diploidAloe morijensis.Two forms of this species have been described, one with fibres only and few exudate components and another with both fibres and aloin cells and an exudate containing compounds of the tetraploid species. A line of diploid plants similar in anatomy and chemistry to the first form is represented byA. fibrosaandA. babatiensiswhile a line of tetraploids with affinities to the second form is represented byA. nyeriensis, A. cheranganiensis, A. elgonica, A. daweiandA.yavellan

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1986.tb01439.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1986.tb01440.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY