中国广义当归属及其相关类群的叶柄结构研究

Anatomical Study on Petiole of Angelica sensu lato and Its Allies from China

对中国38种广义当归属及其相关类群植物的叶柄进行了比较解剖学研究,考察了其横切面形状、髓腔的有无、周缘变化、厚角组织的形状和数目,以及维管束的数目和排列等基本特征,为该类群的分类鉴定和系统进化研究提供解剖学依据。结果表明:上述特征呈现出丰富的多样性和良好的种内稳定性,说明叶柄解剖学特征具有重要的分类学意义。综合上述特征,将广义当归属植物及其相关类群的叶柄划分为4个类型:中空环状类型(Ⅰ)、Φ形维管束型(Ⅱ)、U/V形维管束型(Ⅲ)、同心圆形维管束型(Ⅳ)。依据各类型的结构特点,认为该类群叶柄结构可能的演化关系为:实心叶柄是次生类型,中空环形叶柄(单轮环形维管束)相对原始,Φ形维管束型叶柄是过渡类型,而U/V形维管束型和同心圆形维管束型叶柄是相对高级的演化类型。

The anatomical comparison of petioles from 38 species in Angelica sensu lato and allied taxa from China involved the shapes of cross section, smooth or undulate margin, the presence of cavity, the shape and number of collenchyma, and the number and arrangement of vascular bundle, which possessed rich diversity and intraspecies stability exhibiting taxonomic significance in those taxa. Based on these petiolar charac- ters,four types of petioles could be recognized： Hollow-ring type （ Ⅰ ） ,Ф-type （ Ⅱ ） ,U/V-type （ Ⅲ ） ,Multi- ring type （IV）. Moreover, the potential evolutionary trends of petiolar structure in this group were also suggested：solid petiole was derived;the Hollow-ring type seemed relatively primitive,the Ф-type was tran- sitional, and both U/V-type and Multi-ring type were relatively developed.