THE PLANT ECOLOGY OF Dh'AKLNSBKKG ItANGE. 558 



9. CLIFF VEGETATION. 



Following- Oettli/ we divide this type into Lithopliytes and 

 Chomophytes, the former being exclusively cryptogamic and 

 consisting of algae, lichens, and bryophytes, which colonise 

 the bare rock faces, and the latter being the plants of the 

 rock ledges and ci'evices. Much further collecting and 

 naming of species must be done before the ecology of this 

 type can be adequately dealt with. Collections have been 

 made by the writer and sent to various specialists, but some 

 time must elapse before they can be Avorked up. Nor has it 

 been possible to touch more than the fi'inge of the subject, 

 even in so far as concerns the work of exploi-ation. An 

 ■outline of the ecological classification is given so far as 

 present information permits, but as our knowledge increases 

 further subdivision will doiibtless be possible. 



LiTHOrHYTES. 



The first plants to invade the bare rock faces are various 

 blue-green algte. The associations of these cover enormous 

 ai'eas of the cliffs, especially the cave-sandstone cliffs, and are 

 strikingly apparent from a distance as longitudinal black 

 strips. Hy the invasion of fungi, they are changed into 

 lichen associations, giving a variety of colours to the rock 

 face — black, green, yellow, red, grey, or white — but the lichen 

 associations, though probably much more numerous in point 

 of species, are not of such importance ecologically nor, as far 

 as the writer's observation goes, nearly so extensive as the 

 associations of Cyanophycea?. 



With regard to a portion of the Drakensberg collection 

 made by the writer, Dr. Fritsch writes as follows : 



No. 104 (Goodoo Pass, 6000 ft. September 19tli. 1915). 



This is a composite growth of Cyanophycete, consisting in the 

 main of four forms, viz. Stigonema informe Kutz., forma; S. 

 hormoides Bornet et Flahimlt, forma; Scliizotlirix epiphytica 

 n. sp. ; Glceocapsa sanguinea Kiltz. These appear to form an inti- 



' Oettli, M., ' Beitriige z. Okologie der Felsflora,' Zurich, 1905, 



