Phylogeny of the Leucas group (Lamiaceae)

Interrelationships within the Leucas group have been investigated using cladistic analysis of gross morphological, anatomical and cytological data. Fifty species were sampled from Acrotome, Ballota, Isoleucas, Leonotis, Leucas, Moluccella and Otostegia. Different analyses were made, with and without continuous characters, and with and without characters with overlapping states. The result suggests that continuous characters and characters with overlapping states may contain a considerable amount phylogenetic information. The result also reveals that Leucas is paraphyletc with Acrotome and Leonotis as subgroups, but no changes in the genus delimitations have been proposed. The endemic Leucas species from Asia (excluding Arabia) and Socotra form monophyletic groups. The African Leucas milanjiana is excluded from the Asian section Plagiostoma Benth. Leucas is suggested to have originated in northeast tropical Africa, and to have migrated from this area over Arabia to the Indian subcontinent