Musci Austro-Africana III. Alpine mosses of Lesotho

Abstract

In reference to vegetation, the term Afro-alpine (White, 1983) refers to the plants found in a region of extreme floristic impoverishment on the highest mountains of Africa. This phytogeographic region is not contiguous, but exists as a series of islands (archepelago) extending from Mount Ras Dashen in Ethiopia to the Drakensberg of southern Africa. The kingdom of Lesotho is situated in the foothills and mountains of the Drakensberg and encompasses most of the Afro-alpine vegetation in southern Africa. The mountainous region of Lesotho consists of a deeply dissected plateau with elevations of 2290 to 3484 m. Two ecological elements are supported in this region, i.e., alpine and subalpine. The alpine element exists between 2860 and 3484 m and occupies a narrow strip along the Drakensberg escarpment in Lesotho, western Natal and northeastern Cape Province of South Africa. The vegetation of this element consists mainly of a heath-grassland interspersed with meadows and small bogs. Recent road improvements have provided access to bryologically unexplored areas of the higher Drakensberg. During preliminary phases of work on the mosses for the Flora of Southern Africa (Magill, 1982), a collecting trip to the Afro-alpine region of Lesotho was undertaken. The collections gathered during this trip clearly indicated that the Afro-alpine mosses of Lesotho and western Natal represented a distinct moss element previously unrecognized in Africa. New records from that first trip included the first report of Abietinella abietina in the Southern Hemisphere (Magill & Schelpe, 1979), the first collection of Bryoerythrophyllium in southern Africa and new species of Barbula, Husnotiella (Magill, 1982) and Ptychomitrium (Magill & Schelpe. 1979). A return trip to the region in 1984 has uncovered five new generic records for the African continent and a new genus of Bartramiaceae (Magill, 1987). These mosses appear to be members of a 'world-wide' alpine moss flora. It seems probable, therefore, that they will also be found in other high altitude areas farther up the Afro-alpine archipelago, paralleling their distributions in the Americas and Asia.