摘要:

Thirteen of a group of 91 hybrids betweenAloë rauhiiandA. daweicontained either numerical or structural chromosome aberrations. Three aneuploids were found, also one dicentric, one reversed duplication and nine deletions of which two occurred in a single individual. Some of these mutations were shown to have a direct effect on the expression of leaf epidermal characteristics as seen in surface view using an S.E.M. Others had different effects or none. The deletion of part of the long arm of an L1chromosome had the greatest effect, and it is suggested that important genes governing the organization of the leaf epidermis are located in this region

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1978.tb01368.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

Thymus vulgaris L. is a gynodioecious species with hermaphrodites (mF) and females (mS) widely distributed in southern France and in which reproduction of which is exclusively sexual. Numerous samples have been collected in the French Mediterranean region and the percentage of mS varies from 5 to 95% in different populations. By studying environmental conditions—the area covered at ground level by vegetation, stones and rocks—high percentages of mS are found to be related to a high vegetation cover and an absence or a scarcity of stones. Grasslands and old fields favour mS, while rocky sites favour mF. This relationship, which has been found both on the plains and on a mountain, is related to the most important reproductive characteristics of T.vulgaris—genetic control of male sterility, mode of pollination, percentage of selling and seed production. These relationships agree with the assumption that unstable environmental conditions such as grasslands or old fields in southern France favour maximum seed production and outcrossing. The greater stability of uncultivated areas such as rocky sites allows for the maintenance of autogamy. Consequently, it is natural selection which adjusts the percentage of male sterility in natural populations ofThymus vul

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1978.tb01369.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

The reproductive capacities of the females (male‐steriles or mS) ofThymus vulgaris L.have been investigated, in terms of size and weight of plants, seed production, germination ability and pollination. The data, collected during nine years under controlled conditions and in natural situations are discussed in comparison with the results known in the literature. It is suggested that the large diversity of characteristics promoting sexual polymorphism could justify the high and variable rates of mS met in natural conditions inT. vulgari

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1978.tb01370.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

The diverse relationships of the main differential leaf and nodal anatomical characters of a number ot artificialIlexhybrids and their parents are compared. The marginal sclerenchyma strands character is not transferred to hybrids when differential. The lignification of the unspecialized abaxial epidermal cells is dominantly inherited, except in one hybrid. The development of a distinctive adaxial hypodermis is usually suppressed in hybrids when one of its parents is lacking in this character. New characters are reported for hybrids ofIlex aquifolium × opaca, where the vasculation of petiole and midrib and the presence of periclinal subdivisions in the adaxial epidermis constitute features not known from either parent species.The possible significance of the four different ways of expression of parental characters in the hybrid offspring is discussed with reference to: genetic control of anatomical characters; the identification of hybrid material; the evolution of leaf anatomical diversity inIlex, and the systematic value of leaf anatomical characters

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1978.tb01371.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

A new ontogenetic classification of stomatal types is proposed which replaces the three ontogenetic types of Pant (1965) with seven new ones. The new classification clearly differentiates between the developmental involvement of the subsidiary cells and the purely structural relationship of the neighbouring cells. All known, and hypothetical, ontogenetic pathways of stomatal development can he incorporated into the new classification.An, hitherto unknown, ontogenetic type which incorporates neighbouring, mesogene subsidiary, and perigene subsidiary cell elements into the stomatal complex is described from the fern,Polypodium vulgareL.

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1978.tb01372.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

The concept of subsidiary cells is discussed in the light of the existing literature correlating ontogeny arid mature structure. The protodermal origin of each epidermal component is illustrated and explained and the status of the ontogenetic classifications of these components has been analysed and discussed. Terminology is also defined and discussed.

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1978.tb01373.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1978.tb01368a.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY