中国水青冈属 （壳斗科） 叶结构及分类学意义

叶结构对壳斗科(Fagaceae)现存植物和化石的鉴定具有重要意义。通过对水青冈属5种植物叶结构特征进行细致的研究，结果发现水青冈属植物叶脉有羽状弓形脉、羽状半达缘脉两种类型；三级脉有波状对生贯穿、互生贯穿及混合贯穿三种类型；小脉缺失、简单无分支或一次分支；脉间区发育良好，网眼有三边形、四边形和五边形三种类型，排列规则；具齿种类叶齿由齿主脉和齿侧脉构成，齿侧脉环状。研究结果表明水青冈属二级脉与更高级脉序形成的结构稳定且存在种间差异，具重要分类学价值。基于水青冈属叶结构特征观察结果，本次研究编制了水青冈属植物的分种检索表；参照已有研究结果并结合重要外部形态学特征，编制了壳斗科相关类群分属检索表。

Leaf Architecture and Its Taxonomic Significance in Fagus (Fagaceae) within China*

Leaf architecture is a key diagnostic feature used to identify both fossil and extant plants. This is especially true in the Fagaceae. In this paper, we report a comprehensive study of leaf architectures of five species of Fagus (Fagaceae) in China. Our results show that venation pattern is restricted to the semicraspedodromous and brochidodromous types, tertiary veins are sinuous opposite percurrent, alternate percurrent, and mixed percurrent, and that veinlets are absent or unbranched or branched once. Areoles are well developed and of irregular triangle, quadrangle and pentagonum in shape. They are regularly arranged and a tooth is formed by the principal and accessory veins, with the tooth accessory vein being looped. Leaf margins are sinuous or sinuous with teeth. Our results also indicated that the secondary vein and higher level vein features were stable characters, that differed among the five species. They could be used, therefore, as important diagnostic features for identifying these species. Based on the differences and similarities of leaf architectures, keys used to identify Fagus species in China were revised. Moreover, based on a comparison of our results with those of former leaf anatomy studies in the Fagaceae, a key based on leaf architecture of Fagaceae genera was also revised.