关键词: 柳属, 叶表皮, 扫描电子显微镜, 微系统特征, 分类学意义

Abstract:

 In this paper, twentyeight species of the genus Salix, with similar phenotypic characters, were selected to study the leaf epidermal microfeatures under Scanning Electronic Microscope (SEM). Seven types of wax layer are totally detected in those species, including smooth layer, crust, fissured layer, nonentire platelets, membraneous platelets, conicoids and scalelike conicoids. Among those types, conicoids and scalelike conicoids are exclusively found in Salix, while nonentire platelets and membraneous platelets in Salix are depicted for the first time. The microfeatures of leaf hairs of Salix plants under SEM are less diversified than their macrofeatures, with detectable microfeature variations on hair length, density and degree of curve (straight, slightly curved and deeply curved). In conclusion, our results showed leaf epidermal microfeatures of wax layer types and stomatal apparatus are relatively unchangeable, which are valuable in the discrimination of similar Salix species. The Salix species from colder region and/or higher elevation usually bear diverse microfeatures, which might be adaptive evolution to colder environments.

Key words: Salix, Leaf epidermis, SEM, Microfeatures, Taxonomical significances