488 PHYTOGEOGRAPHICAL REMARKS. 



reaching noo metres, are covered with it. To what extent the wood chan- 

 ges its constitution at this height, is unknown. It has been noticed that on 

 the high tops the trees are lower than on the plain, but extensive descrip- 

 tions are entirely lacking. Bare tops are very rare. Among these may be 

 mentioned the Voltzberg on the Coppenam and some tops on the Litanie 

 and Tapanahoni, e. g. the Knopaiamoi and the Teeboe. Here it is the com- 

 position of the soil that prevents the growth of trees. Such bare tops are 

 often overgrown with Bromeliaceae (Plate I) of which Pitcairnia nuda seems 

 to be one of the commonest. This plant was already noticed by Kappler 

 in 1861 when ascending the "Piton Vidal", as appears from his description 

 of that expedition. In 1903 and 1905 it was found in great masses in the 

 same place and also on the bare tops on the Upper Tapanahoni river by 

 Versteeg. Portulaca pilosa seems to occur commonly here also, as well 

 as Manihot utilissima which was found in these [places entirely wild, as 

 well by Kappler as by Versteeg. From fissures in the rocks in which the 

 roots of large plants may develop, species of the genus Clusia rise very 

 frequently, while the often entirely leafless crowns of Cochlospermum, 

 covered with bright yellow flowers, are visible at a great distance. Groups 

 of Cocos fiexuosa are noticed in many places, while Cecropia here also 

 is very numerous. 



Whereas most Surinamian rivers from their source to their lower course 

 flow through a river-bed which slopes strongly and irregularly and so form 

 waterfalls and rapids throughout their upper course, this is not the case 

 with the Coppenam R. and the Saramacca R. The upper course of these 

 rivers is situated in a valley, consisting of alluvium in which the rivers 

 have dug out a narrow but often very deep bed, so that their backs are 

 in many places high and steep. On this soil the primitive wood often 

 has another appearance, which is caused not so much by the trees as 

 by the enormous quantities of Geonoma which here cover the ground. 

 Since the river is mostly very narrow here and consequently little light 

 penetrates into the wood, the banks bear little vegetation, so that one may 

 notice without difficulty that here also the trees are at relatively great 

 distances from each other. The appearance of the river becomes quite 

 different in places where the banks are low and often flooded. Here high 

 trees become quite secundary and a dense wood of shrubs, chiefly Inga, 

 covers the soil ; in such places the river is often quite obstructed by the 

 growths and one has with great difficulty to cut a passage from the boat. 

 Characteristic of the marshy soil are the grouplets of Mauritia flexuosa, of 

 Euterpe oleracea and of Ireartea exorrhiza which occur again everywhere. 

 Blooming plants are abundent here The purple Passiflora coccinea and the 

 blue Solanum pensile climb upwards in the low shrubs. A spare Hymenaea 

 raises its crown far above the low vegetation and occasionally one meets 

 extensive plains with species of Guadua, resembling Bambae. Where the 

 bank becomes a little higher again, Oenocarpus is noticed ; big, shrublike 



