丛枝蓼和长鬃蓼鉴别性状变异式样的数量分析

A QUANTITATIVE ANALYSIS OF THE VARIATION PATTERN OF DIAGNOSTIC CHARACTERS OF THE POLYGONUM POSUMBU COMPLEX

本文运用散点图(scatter diagram)和柱状图(histogram)方法对丛枝蓼(P.posumbu Buch.-Ham.ex D.Don)、长鬃蓼((P.longisetun De Bruyn)及圆基长鬃蓼(P.longisetum var.rotundatun A.J.Li)的主要鉴别性状进行了统计分析,研究结果表明:花序长度、苞片缘毛长度及小花梗与苞片的相对长度种间差异不明显,不宜作为鉴别性状;根据各类群特征相关变异的程度及特征变异范围,作者认为长鬃蓼不足以成立独立的种,支持Steward 1930年所作的分类处理,将长鬃蓼降级作为丛枝蓼的变种。

Taxa of the Polygonum posumbucomplex, including P. posumbu, P. longisetum and its var. rotundatum, are taxonomically perplexing. By means of conventional taxonomic methods, it is difficult to discriminate them from one another. Basing upon herbarium materials of about 100 sheets of specimens collected from 11 provinces in China, a quantitative analysis of the correlations between certain key characters was thus made by applying the methods of pictorialized scatter diagram and histogram so as to reexamine the validity of the above taxa. Results from both methods have indicated that this complex could be divided into three parts: (1) Individuals-with branching repent stems without a central axis, blades usually ovate, ap-pressed hairy and with caudate tips, agreed well with typical P. posumbu; (2) Individuals-with more generally erect, stems, leaves lanceolate and usually glabrous, agreed with P. longisetum; (3) Individuals-characterized by angusti-lanceolate blades with truncate-rounded or subcordate base, agreed with P. longisetum var. rotunda turn. Both diagrams also Showed that these three parts are so closely related to one another that they are by no means strictly seperable. Thus it is better to treat them all as varieties of the said complex. A propertaxonomic treatment should include the reduction of P. longisetum to a varietal rank of P. posumbu as well as a combinatio nova P. posumbu var. rotundatum (A.J.Li) J.W.Wang.