Analysis on the Characteristics of Leaf Venation of Uraria Desv. and Its Relative Genera in China

By exploring the variation pattern and taxonomical significance of the leaf venation characteristics between the genera and species of Uraria Desv. and its relative genera (Christia Moench and Urariopsis Schindl.), it could provide data for the identification, development, utilization and protection when they were regarded as the medicinal plant resources. The leaf venation characteristics of 12 species of this group were observed and described by using the cleaning method to make the specimens. The principal component analysis and cluster analysis were carried out based on the characteristics of leaf venation, and a classification retrieval table of the species was compiled. The results showed that: (1) The characteristics of the leaf venation of Uraria Desv. and its relative genera had consistency, which were mainly reflected in the fact that they were straight pinnate veins, the inter-secondary veins were compound (except for Christia obcordata), the tertiary veins were both reticular and penetrating, and the last veins of the leaf margin converged at the leaf margin. (2) The characteristics of the leaf venation with taxonomic value among the genera or the species within the genera included the leaf shape of the terminal leaflet, the length-width ratio of the terminal leaflet, the logarithm of the secondary veins and the interveinal distance, the angle between the secondary vein / tertiary vein and the main vein and its change, the areole development, and the branch of blind veins. (3) The cluster analysis showed that the 12 species were clustered into two major branches, and the species of Uraria Desv., Christia Moench and Urariopsis Schindl. were not clustered into one branch. Among them, the species of Christia campanulata and Uraria oblonga were clustered into one branch with the species of Uraria Desv., while the species of Urariopsis brevissima was clustered into one branch with the species of Christia Moench, showing a relatively close genetic relationship. The results showed that the leaf shape of the terminal leaflet, the length-width ratio of the terminal leaflet, the type of the secondary veins, the logarithm of the secondary veins and the interveinal distance, the angle between the secondary vein and the main vein and its change, the angle between the tertiary vein and the main vein and its change, the areole development, and the branch of blind veins were the characteristics of the leaf venation with taxonomic value of Uraria Desv. and its relative genera.