Aquatic and wetland plants of Southern Africa an identification manual for the stoneworts (Charophytina), liverworts ( Marchantiopsida), mosses (Bryopsida), quillworts (Lycopodiopsida), ferns (Polypodiopsida)and flowering plants (Magnoliopsida) which grow in water and wetlands of Namibia, Botswana, Swaziland, Lesotho and Republic of South Africa - Cook, Christopher D. K. (Backhuys, 2004)