Study On Numerical Taxonomy Of Quercus L. (Fagaceae) From China

By examing and measuring specimens of genus Quercus L. in seven important herbariums of China, the phylogeny and taxonomy of 53 species of Quercus (including 4 varieties) from China, including the relationship between sections of Quercus, relationship between species of Quercus, and the Quercus dentata complex, were studied in the present paper. Firstly, based on morphological characters of 49 species and four varieties of Quercus from China, we measured 25 qualitative and 18 quantitative characters. In cluster analysis and principal components analysis, the result revealed that Quercus were divided clearly into five phenetic groups, namely section Aegilops, section Quercus, section Brachylepides, section Engleriana and section Echinolepides. Principal components analysis obtained the same result as the cluster analysis, but the cumulation rises slowly and that of the first three principal components presented only 50.4%. These results indicated that the principal taxonomic characters exist in Quercus for taxonomy still, only in the period of evolution, several different phenetic groups were produced in the genus Quercus. The result was useful for identifying closely related species of Quercus as well. Secondly based on morphological characters of 15 species and three variations of section Quercus from China, we measured 32 quantitative and 18 qualitative characters. In cluster analysis and principal components analysis, the results indicated that Q. griffithii is closely related to Q. malachotricha in phenetic in this group. Principal components analysis also obtained the result that the cupule bract is the main character of taxonomic significance, and the number of secondary veins on each side of midvein could not be regarded as the main taxonomic character in this group. This paper suggests that Q. malachotricha should be treated as a synonym of Q. griffithii. And at the same time, this paper doesn't support the unition of Q. mongolica and Q. wutaishanica. Thirdly, the Q. dentata complex from China are composed of six species of Q. dentata, Q. fangshanensis, Q. fengchengensis, Q. stewardii, Q. hopeiensis and Q. mongolicodentata, which are quite similar in morphology. By the analytic method of phytogeography, clustering analysis, principal components analysis, canonical discriminant functions analysis and morphological characters analysis of the 100 specimens of the complex and its closely related taxa Q. aliena var. acuteserrata, Q. aliena var. pekingensis and Q. mongolica from China, the author obtain the result that Q. fangshanensis, Q. fengchengensis, Q. stewardii, Q. hopeiensis and Q. mongolicodentata are probably hybrids between Q. dentata and other closely related taxa Q. aliena var. acuteserrata, Q. aliena var. pekingensis and Q. mongolica, in line with the view of Huang et al's. And the result supports that Q. stewardii be viewed as a geographical race of Q. dentata (Camus,1936-1954), because of its particular morphological characters, geographical distribution and ecological habitat. As seen from the result above, the method of numerical taxonomy plays an important role in taxonomy of Quercus.