97 



tains to tlie east of the Namib are not so dry, while towards 

 the north, in Damaraland and Ovamboland, we gradually 

 pass into a distinct tropical, and much moister region, which 

 remains largely unexplored, but which seems to have much 

 in common with the areas of similar latitude on the eastern 

 side of the continent. In all the drier parts mentioned, the 

 vegetation is of an open type, and the plant succession has not 

 progressed beyond the initial stages, which in this case are 

 also the final stages. 



An examination of the list of grasses published by Schinz 

 shows that 15 species belong to the Andropogoneae, 40 to the 

 Paniceae, 26 to the Stipeae, and 32 to the Eragrosteae, all of 

 which are tropical or sub-tropical tribes, and between them 

 include over 70 per cent, of the total grass flora. The great 

 South-Western tribes Aveneae, Festuceae, and Phalarideae, 

 are hardly represented. This at once establishes the important 

 fact that the grasses of the Western region, like the rest of 

 the flora, have much closer affinities with those of the Eastern 

 Grass-veld than with those of the Macehia. The most impor- 

 tant Western genera are: Eragrostis (25 species), Aristida 

 (24), Panicum (18), Andropogon (13), Pennisetum (8), Sporo- 

 bolus (7), Triraphis (7), Diplachne (6), Setaria (5), Anthephora 

 (4). Total, 117 specie.s, or again nearly 70 per cent, of the 

 whole. If, however, we exclude the distinctly tropical 

 northern portion, from which a large number of new species 

 have been recorded, the numbers are reduced, and by far the 

 most important genus, both floristically and ecologically, is 

 Aristida, in fact most of it might be described as Aristida 

 veld. The germs Aristida, especially in the species belonging 

 to the section Stipagrostis, is peculiarly a desert type. 



A study of the lithosere in this region should prove 

 extremely interesting. Lichen vegetation appears to be more 

 developed here than in any other part of South Africa. In 

 the list of lichens given by Schinz the genera Amphiloma, 

 Blastenia, BueUia, Combea, Lecidea, Gasparrinia, Parmelia, 

 Physcia Pysona, Ramalina, Roccella, Theloschistes, and 

 Xonthoria are represented. The Bryophyta are poorly repre- 

 sented and hardly enter into the plant succession. As far as 

 the grasses are concerned, our information at the present time 

 only permits of a provisional habitat classification as follows : 



A. Coast Belt (Coast line and Namib). 



(a) Sand-dunes, sandy plains and gravel-flats. Eragrostis 

 cyperoides, E. spinosa, E. denudata, Sporobolus pungens, 

 Aristida ciliata, A. dregeana, A. obtasa, A. sdbulicola. 



