瑞香属和荛花属的数量分类研究.

Daphne and Wikstroemia are members of subfamily Thymelaeoideae which belongs to Thymelaeaceae. There are 95 species(varieties)in genus Daphne, 52 of which distribute in China. There are 70 species(varieties)in genus Wikstroemia and 49 species(varieties)can be found in China. Southwest China is the species diversification center of the two genera. Petals of Daphne and Wikstroemia degenerate and usually form circular disc or linear disc scale. Conventionally, the shape of disc and type of fruit were used as crucial characters to separate the two genera. The circular disc frequently occurs in Daphne while linear disc scale occurs in Wikstroemia. Meanwhile, fruit is usually succulent berry in Daphne, but Wikstoemia has dry or leathery fruit, and sometimes enclosed by persistent calyx. However, alternational characters among species of the two genera have been reported and some species have both kinds of characters. In this study, 32 morphological characters were used in the numerical taxonomy of 77 species(varieties)from genus Daphne and 62 species(varieties)from genus Wikstroemia with clustering and principal component analysis. UPGMA clustering results revealed that neither genera formed monophyletic group species from the two genera clustered together. In the principal components analysis, the cumulative percent of the first three principal components presented 35.56%, while the conventional taxonomic characters, such as the disc shape, phyllotaxy and the fruit type, contribute minor effects on the first three components. So, taxonomic distinguishable characters of the two genera could not separate them clearly. Three-dimensional scatter plots based on principal components analysis revealed that species from both genera embeded with each other and did not separate two genera as monophyletc group. Neither clustering analysis nor principal components analysis supported the traditional taxonomy that Daphne and Wikstroemia were naturally monophyletic groups. [ABSTRACT FROM AUTHOR]