Revision of the Micromeria (Labiatae) in tropical to southern Africa and on the Arabian Peninsula

The material of Micromeria s.s. (M. sect. Micromeria) from tropical to southern Africa and the Arabian Peninsula is revised. The endemic Ethiopian M. unguentaria Schweinf. is retained as a species, while the other African and Arabian material of Micromeria is included in M. imbricata (Forssk.) C. Chr. M. imbricata is divided into the following three varieties: var. imbricata, which is very polymorphic, widespread in the African highlands, and also occurs in Arabia; var. rhodesiaca (Elly Walther & K. H. Walther) Ryding, which occurs in the highlands of Malawi, Mozambique and Zimbabwe; and var. villosa (Elly Walther & K. H. Walther) Ryding, which occurs in montane to alpine areas of Ethiopia and East Africa. Discontinuities in the variation within var. imbricata, observed at some localities, are suggested to be a result of partial autogamy. Problems with delimitation between M. imbricata, the East Asiatic M. biflora (Buch.-Ham. ex D. Don) Benth. and some Mediterranean species are discussed. (C) 2007 The Linnean Society of London, Botanical Journal of the Linnean Society, 2007, 155, 427-446.