Taxonomic revision of Geranium sections Batrachioidea and Divaricata (Geraniaceae)

Geranium subg. Robertium (Geraniaceae) comprises eight sections, of which section Batrachioidea and section Divaricata are revised here. Geranium sect. Batrachioidea consists of four species centered in Eurasia, between the Mediterranean region and the Himalaya Mountains, although they have also expanded to many temperature areas in America, South Africa, and Australia. In contrast to the current literature, ne consider G. brutium to be a synonym of G. molle. We also accept G. aequale to include plants similar to G. molle but with smooth, mericarps, Geranium sect. Divaricata comprises two species, one widespread between the Mediterranean region and the Himalaya Mountains and the other endemic to the Caucasus. A cladistic analysis using a data set of 15 characters showed that both sections are well supported by synapomorphic features. Conversely, no new character (other than pollen color) was found to support a relationship between them. Brief accounts are also given of chromosome number, hybrids, and diagnostic aspects of morphology;. Nomenclature for all species is reviewed, 32 lectotypes are designated, and descriptions, distribution maps, and illustrations are provided.