FLORISTIC REGIONS 113 



The vegetation is mainly xerophy tic. The Karroo-bush 

 (Acacia horrida Willd.) is everywhere. In the west, 

 wet winters and dry summers are accompanied by a 

 typically sclerophyllous woodland, of which the Pro- 

 teaceous Silver- tree (Leucadendron argenteum R. Br.) 

 may be taken as a type. In the east, dry winters and 

 a moist warm summer produce savannah conditions, 

 forest-growth being restricted to the " kloofs " or river- 

 valleys. The upper and middle karroos in the west 

 (over 3000 feet and over 2000 feet respectively) bear 

 small shrubby Composites, such as the Rhinoceros-bush 

 (Stcebe Rhinocerotis L. fil.); and in August the middle 

 terrace becomes luxuriantly green for a few weeks and 

 is carpeted with blossoms of Composites, Liliacece, Mesem- 

 bryanthemum , etc . The southernmost and lowest terrace, 

 the " Bush," as it is termed, is, perhaps, the richest 

 area for species of its size in the world. Cactus-like 

 Euphorbias, Stapelias, Irises, Gladiolus, Ixia, Lilies and 

 other bulbous plants, no less than 400 species of Mesem- 

 bryanthemum, Crassulacece, such as Crassula, Cotyledon, 

 and Kalanchoe, tuberous-rooted Pelargoniums, Oxalis, 

 " everlastings," such as Helichrysum and many other 

 Composite, terrestrial Orchids, such as Disa, and numerous 

 species of Aloe are among the most characteristic. Just, 

 however, as in Ireland we have luxuriant vegetation 

 with few species, so here conversely the number of 

 species by no means implies luxuriance. 



The northern extension of this flora is of considerable 

 interest. Various South African forms occur in the 

 sub-alpine zone on the equatorial Kilima-njaro, a Protea 

 and others in the Abyssinian Highlands, and many of 

 these also on the Kameruns in the west. The South 

 African affinity of the flora of the remote volcanic island 

 of St. Helena is shown by the presence there in an 

 assemblage of 50 indigenous species of flowering plants 

 and 26 Ferns, of the former of which 40 are endemic, 

 17 belonging to endemic genera, while 10 of the Ferns are 

 also peculiar of Pelargonium and Mesembryanthemum. 

 The East India Company's goats and introduced plants 

 have, however, nearly exterminated this native flora. 

 Pelargonium also extends into Southern Europe and Asia 

 Minor. Various species of Erica, Lobelia, Gladiolus, and 

 other genera " more nearly allied to Cape species than 

 they are to each other," with Sibthorpia, Ulex, Genista, 



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