PRESIDENTIAL ADDRESS SECTION C. 75 



-e.g., the Tugela Valley and Lower Mooi River Valley. It is more 

 xerophytic than climax Thorn Veld, though it does contain a 

 sprinkling of Thorn Veld Acacias and other species. It contrasts 

 very sharply with Midland scrub and forest. It resembles in some 

 of its ecological characters the Fish River scrub in the Albany and 

 Bathurst districts of the Cape Colony, and it has floristic connec- 

 tions with the vegetation of dry kopjes in the Transvaal as well as 

 with the Tropics further north. According to Dr. T. R. Sim the 

 component species can be arranged roughly in the following order 

 of importance : — Croton gratissimus, C. zambesicus, C. menyharti, 

 C. rivularis, Vitex mooiensis, V. rehmanni, Heeria panicidosa, 

 Euphorbia tirucalli, E. ingens, E. cooperi, E. tugelensis, Ficus 

 natalensis, and other species, Tarchonanthus camphoratus, Capparis 

 albitrunca, Schotia brachypetala, Ptaeroxylon utile, Clausena 

 inaequalis, Euclea lanceolata, E. undulata, E. natalensis, Rhus 

 (many species), Brachylaene elliptica, B. racemosa, Commiphora 

 harveyi, C. caryaefolia, Dichrostachys nutans, Dombeya natalensis, 

 JD. rotund if olia, Aloe spp., with numerous climbing Asclepiadaceae, 

 species of Clematis, etc. Parasitic species of Viscum and Loranthus 

 are common. 



H. Mountain (Drakensberg) Forest. In the scrub zone 

 My r sine africana is a frequent pioneer followed by Erica spp., Clif- 

 fortia spp., Leucosidea sericea, the last-mentioned often dominant 

 over wide areas. The climax forest has Podocarpus falcata often 

 dominant in South Drakensberg forests. Curtisea faginea, Rapanea 

 rnelanophloeos, Celtis rhamni folia are other characteristic species. 

 Olinia. d rahensb ergensis is found usually at higher altitudes than 

 the others. 



I. Ngoya Forest, Zululand. This type occupies a number of 

 minor hills and valleys in the centre of a main range instead of the 

 usual shales, sandstones and dolerites. Milletia sutherlandi is com- 

 pletely dominant while Podocarpus is rare. 



8. — The Alpine and Macchia Vegetation of the Drakensberg. 

 This type has strong affinities with the South- Western vegeta- 

 tion of the Cape. The family Compositae is enormously abundant, 

 while the Ericaceae are peculiarly characteristic, and ericoid growth 

 forms belonging to other families, e.g., Cliff ortia, Passerina, etc., 

 are often dominant. It is best developed at altitudes of 8,000 feet 

 and the usual effects of high altitude are shown in the gnarled 

 growth forms, cushion forms, rosette forms, densely woolly cover- 

 ings, etc., but the environmental conditions are so very unstable 

 that all kinds of requirements are met in different spots. There are 

 places with full exposure to the intense light, places with continuous 

 natural shade and shelter; moist spots near the numerous dripping 

 waterfalls contrast with very dry spots, it may be only a yard or 

 two distant ; places where frosts never occur may be quite close to 

 places where the water is frozen into a sheet in winter. All this 

 instability and complexity makes it difficult to sort out the vege- 

 tation into any system of ecological classification. The plant com- 

 munities are as unstable as the environmental conditions. That 



