Taxonomic Revision of Geranium sect. Polyantha (Geraniaceae)
Geranium L. sect. Polyantha Reiche (Geraniaceae) consists of seven species. The highest diversity of the group is located in southwestern China with five endemic species. One species is found in the Himalaya, and another is located in the mountains of Burma. In contrast with some regional treatments, I have synonymized G. ascendens Z. M. Tan to G. moupinense Franch., and G. platylobum (Franch.) R. Knuth to G. hispidissimum (Franch.) R. Knuth. Micromorphological features of indumentum, pollen, and mericarps were investigated by SEM. The presence of pollen with Erodium L’Hér.–type exine ornamentation is confirmed for all species of the section. A new key is provided, as well as new and detailed descriptions. Each species is illustrated and mapped, and three lectotypes are designated.