Taxonomy and phylogeny of two subgroups of Pelargonium section Otidia (Geraniaceae). 1. The Pelargonium carnosum complex

Abstract

This contribution deals with the taxonomy and phylogeny of the  Pelargonium carnosum complex, a group of closely related taxa of Pelargonium L’Hér. section  Otidia (Sweet) DC. (Geraniaceae) that is distributed in the winter rainfall area of South Africa. According to molecular analyses via AFLP, P. adriaanii M.Becker & F.AIbers,  P. carnosum (L.) L’Uér., P.  ferulaceum (C'av.) Willd. and P. polycephalum (E.Mey. ex Harv.) R.Knuth form a monophyletic clade. Although hybridization may occur between the taxa, three are assigned to specific rank. The fourth taxon, P. ferulaceum is recognized as a subspecies ot'P carnosum. As is implied from the occurrence of morphological intermediates and partly from molecular evidence,hybridization does not only occur among the taxa in this complex but also involves species closely related to this group  (P. panifiorum J.C.Wendl., P. laxum (Sweet) G.Don, P. dasyphyllum R.Knuth). For the taxa in the P. carnosum complex, distribution areas are delineated and diagnostic features that have until now remained obscure, are outlined.