THE PALAEOTROPICS 169 



The high forest stops at about 6,000 feet, a remarkably low 

 point when compared with high mountains in much colder 

 regions, as in the Rocky Mountains and Siena Nevada in Amer- 

 ica, or the Himalayas. 



Above the forest zone, the mountain is covered with a grass- 

 formation, interspersed up to 2,500 metres, with patches of 

 stunted trees, which are covered with a heavy growth of 

 epiphytes. 



The summit of the mountain has a flora which includes many 

 familiar types of temperate climes, such as St. John's wort (Hy- 

 pericum), buttercups, foreget-me-not, hound's tongue (Cynoglos- 

 sum), milfoil (Achillaea), Stachys, Veronica, Galium, plantain, etc 1 



East Central Africa 



The region near the headwaters of the Blue and White Nile 

 is an elevated rugged plateau of steppe character. It is largely 

 open grass-land but there are also savannas and dry forest in 

 places. The baobab and several species of Acacia are wide-spread 

 in this region, and two characteristic palms, the Indian fan- 

 palm (Borassus flabelliformis) and the dom-palm (Hyphaene 

 Thebaica), are common, especially in the narrow forest areas 

 along the rivers. 



This plateau region is enclosed by mountains which conned 

 with the highlands of Abyssinia, and are the source of most of 

 the water that feeds the Nile. 



The White Nile, especially, and its tributaries are in many 

 places bordered by extensive swamps, formed by the flood water-. 

 These marshes contain many characteristic aquatics, among 

 which the famous papyrus is especially conspicuous. Between 

 the clumps of papyrus, reeds, rushes, and other tall marsh plant-. 

 are solid patches of "sudd," dense turfy masses of shorter grasses 

 and other plants, which completely hide the surface of the water, 

 giving the appearance of solid ground. Detached masses of 

 sudd, floating in the open water, are often a serious hindrai: 

 to navigation. 



Along the banks of the rivers, is a belt of forest, in which 

 groves of palms are the most conspicuous feature, bu1 back 



1 For details of the flora of the Great Kamerun, sec Engler, loc. n't. 



