Studies On The Leaf Epidermal Micromorphology And Numerical Taxonomy Of Euonymus (Celastraceae)

Euonymus is the second larger genus of Celastraceae. It mainly distributed in subtropical and warm regions of eastern and western hemispheres. China is the central area of contemporay Euonymus. Different researchers have different views on the division of Euonymus. System location of some species are controversial. So the further study is necessary in the genus. In this study, the leaf epidermal cells features of28species of Euonymus in China were observed using scanning electron microscopy (SEM).30characters of13species of the section Echinococcus were analysed using the numerical taxonomy. Main results were as follows:1. The leaf epidermal cells features of28species of Euonymus in China were observed using scanning electron microscopy (SEM), containing cell boundary, shape of cells, pattern of anticlinal wall, cuticular membrane type. The results revealed that there were various types exist in the leaf epidermal cells of Euonymus. Adaxial and abaxial epidermal cells are different in13species such as E. viburnoides and E. chuii.2. There were significant differences on the leaf epidermal cells features of28species of Euonymus. It can be used as the evidence for the classification. The classical taxonomic treatment as five sections of Euonymus is not supported by this research. But affinitive species usually possess same type on the leaf epidermal cells. E. mengzeanus and E. hystrix is supported as independent specie.3.30characters of13species of the section Echinococcus were analysed using the numerical taxonomy for the first time. The result of cluster analysis showed that the distance between E. americanus and E. chenmoui is the nearest. Two series found by Blakelock in the section is not agreed. E. hemsleyanus and E. angustatus showed far distance with each other. There were significant difference on9characters such as angle of leaf apex et al. They should be considered as separate species. Because the fruit is no prick. E. mengtseanus and E. tengyuehensis should be removed from the section. Because there were no enough research data in crossed region, genetic relationship between E. echinatus and E. subsessilis should be researched in the future.4. The result of factor analysis showed that9eigenvalue of factors were larger than1.18characters had high correlation with factors. It contains6categories (habit, leaf morphology, peunncle form, flower pattern, fruit and prick shape, aril shape). These characters were of significance for classification of section Echinococcus.