A new species of Orthosiphon (Lamiaceae), Orthosiphoncinereus A.J.Paton, sp. nov. from Angola is described and the eight species of Orthosiphon in Angola listed with reference to previous accounts. Orthosiphonnewtonii Briq. is reduced to the synonymy of Endostemontubulascens (Briq.) M.Ashby.
Keywords: Endemic species; southern tropical Africa.