中国藁本属叶柄的解剖学研究

ANATOMICAL STUDIES OF PETIOLE IN LIGUSTICUM FROM CHINA

本文首次观察了我国藁本属(Ligusticum)21种植物的叶柄解剖结构、基本特征和变异幅度。根据叶柄的维管束排列,结合横切面形状、近轴面沟槽的有无及形状、周缘的变化及髓腔的有无等特征,把21种藁本的叶柄解剖分为4个类型。依据各类型的结构特点及植物的外部形态,讨论了这4个类型可能的演化关系。作者认为滇西北地区不仅藁本属植物种类丰富,而且集中了叶柄解剖的全部类型,形态分化活跃,应是这个属的最大变异中心。

Nearly 30 species of Ligusticum occur in China. This paper deals with the petiolar anatomy of 21 species (25 samples) in the genus. The anatomical characters of 21 species are very diverse and listed in Table 1 and Plates Ⅰ,Ⅱ. Comparing the petiolar anatomy of 8 populations belonging to 4 species, it is shown that the anatomical characters of petioles in Ligusticum possess certain stability except with some variations of numbers of vascular bundles within a species, and can be used as a useful taxonomical evidence. According to the disposition of vascular bundles, combined with the shape of the cross section, the presence and shape of the groove on the adaxial side, smooth or undulate margin and the presence and shape of pith cavity, the anatomical structures of petiolies of 21 species are divided into 4 forms (see Fig.1). The probable evolutionary relationships of the 4 forms of petiolar anatomy in the genus Ligusticum are discussed. By analysing the distribution of Ligusticum in Yunnan, it is found that the 4 forms ofpetiolar anatomy and more than two third of total species numbers of Ligusticum are concentrated in northwestern part of Yunnan. Reasonably a conclusion could be obtained that the center of diversity of Ligusticum is possibly in Northwestern Yunnan.