摘要:

A survey has been made of the leaf anatomy of 43 woody species in three montane vegetation types of Isla Margarita, Venezuela, differing in levels of cloud cover (and hence wetness) and exposure to wind. The only character that varies significantly with increasing probability of periodic drought is specific leaf area, which can be related to the higher proportion of deciduous species in the drier habitat. Leaves become significantly smaller and thicker with increased exposure to wind, and have thicker outer epidermal walls and cuticles. Most characters, including stomatal density, guard cell length, palisade: non‐palisade ratios, and the incidence of such features as hypodermis, sclerenchyma, crystals and secretory structures are highly variable and show few or no trends according to habitat. Some of these characters are apparently more constrained by phylogeny than by immediate ecological circumstances. As a contribution to the continuing debate on the significance of xeromorphy in tropical montane forest leaves, it is suggested that low light levels due to cloud cover can be discounted as an important determining factor; in the case of the Isla Margarita vegetation, the need to avoid excessive leaf temperatures may be of greater significanc

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1985.tb00383.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

The leaf ofC. dioneaefoliais composed of two pairs of lobes, each pair resembling a trap of the carnivorous plantDionaea.The anatomy of the leaf was studied to examine the possibility that this species, likeDionaea, is carnivorous. Neither glandular structures, nor trigger hairs could be found, and it was concluded thatC. dioneaefoliais non‐carnivorous. The leaf ofC. dioneaefoliais dorsiventral. The inner surface of each leaf lobe is covered with a thick cuticle with numerous anomocytic stomata. The stomata seem to be functional, not occluded. The outer surface of each leaf lobe is covered with a thin cuticle and has no stomata. The mesophyll is of the conjugate type, with papillae both in the pallisade and in the spongy mesophyll cells. The conductive system is developed to only a limited exten

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1985.tb00384.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

The leaf anatomy of the rhizomatousIrisspecies with ensiform leaves and the related generaPardanthopsisandBelamcandais described. Their isobilateral leaves may or may not have a pseudo‐dorsiventral structure. Variable characters of their leaf blades include: outline in transverse section, height and shape of papillae, form and structure of stomata, transverse section outline of marginal fibre strands and sclerenchy matous inner bundle sheath at phloem and xylem poles, forms of mesophyll arrangement, mesophyll structure and air canals, vascular bundle arrangement and the detailed structure of the larger vascular bundles, distribution of tannin, size and distribution of crystals. The taxonomic and ecological significance of these characters has been evaluated.The anatomical characteristics of 25 supraspecific taxa in three genera are presented and compared in tables. The relationships and evolutionary position of these taxa are discussed. Each of the three subgroups withinIrisappears to be correlated with a syndrome of anatomical characters. Some species currently of uncertain taxonomic position are discussed, and their classification based on anatomical data is suggested.Some characters related to xeromorphy or helomorphy are mentione

ISSN:0024-4074    

DOI:10.1111/j.1095-8339.1985.tb00385.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY