Variation in the form and habitat of Agathosma in northern Eastern Cape.

Tony Abbott, P O Box 111, Port Edward 4295

Tel/Fax (039) 313 2684 Email tabbott@venturenet.co.za

The geoxylic suffrutex known as Agathosma ovata is well-known and wide spread in southern KwaZulu-Natal and the northern Eastern Cape (Pooley 1998). This form only occurs as a suffrutex with many to very many annual to biennial stems which are 2 – 3 mm in diameter and 50 cm in height.

The Cape form of Agathosma ovata known in the southern areas of South Africa is described as a variable shrub, 0.3 – 3 m in height (Bond & Goldblatt 1984).

The Agathosma sp. in the KwaDlambu River, a tributary of the Msikaba River, which forms the southern boundary of Mkambati Game Reserve, grows exclusively within the flood area of these sandstone streams and rivers. The sandstone has been described as the Msikaba Formation (Thomas et al 1992). It is considered to be of marine origin and 300> my younger than the fluviatile Natal Group Sandstones. This formation is the underlying substrate to which the Pondoland Centre of endemism is confined (Van Wyk 1990). Past collections have not revealed the presence of this taxon in any other area in this vicinity.

The Agathosma sp populations appear to have no relationship with those of the suffrutex. Each occurs in all associations with the other from present to absent; no intermediates have been seen and each is confined to its own habitat, the A. sp. to the rivers and the suffrutex to the grasslands.

I believe that two different taxa are involved but there seems to be some question as to what taxon is correctly represented by Agathosma ovata. Voucher, FAA and slide specimens are placed at the Schweickerdt Herbarium, University of Pretoria.

Bond, P. and Goldblatt, P., 1984. Plants of the Cape Flora. National Botanic Gardens, Claremont.

Pooley E., 1998. A Field Guide to Wild Flowers of KwaZulu-Natal and the Eastern Region. Natal Flora Publications Trust, Durban

Thomas, R.J., Marshall, C.G.A., Watkeys, M.K., Fitch, F.J. and Miller, J.A., 1992. K-Ar and ⁴⁰Ar/³⁹Ar dating of the Natal Group, Southeast Africa: A post Pan-African molasse? Pergamon Press, Great Britain.

Van Wyk, A.E., 1990. The sandstone regions of Natal and Pondoland: Remarkable Centres of Endemism. A.A. Balkema, Rotterdam.