222 OUTLINE OF PLANT GEOGRAPHY 



is an extensive plateau, a sort of moorland covered with coarse 

 " lalang " grass and bracken. Except in sheltered places, trees were 

 absent, but where conditions permitted, tree-ferns, palms (Car- 

 yota, Arenga), and some other tropical types were noted; but with 

 these were such characteristic northern plants as elder, raspberries, 

 violets and several coarse Compositae. These grassy plateaus 

 are said to be frequent in the mountain regions of northern Sumatra. 



The western side of the main mountain range has a much heavier 

 rainfall than occurs in eastern Sumatra and the vegetation is 

 said to be extremely luxuriant. In the Padang Highlands, espe- 

 cially in the volcanic districts, the conditions are much like those 

 in western Java, and the vegetation has much in common with that 

 region. 



The forests of the southwest are said to be characterized by 

 unusually large trees, especially some of the Dipterocarps. Forbes 1 

 states that he measured trees whose trunks were 40-50 yards be- 

 fore they branched, and some of them ten to twelve feet in diameter. 

 The species were not given. The principal products of this part 

 of Sumatra are pepper and dammar-gum, the latter derived from 

 several species of Dipterocarps, the most valuable being that ob- 

 tained from Hopea dryobalanoides. These gums are highly prized 

 for fine varnishes. 



Even with its relatively scanty population, the destruction of 

 the forests has been very great, owing to the very wasteful methods 

 employed. Like all half-civilized peoples in a forest country the 

 natives destroy the forest with no thought for the future. The 

 ground is cleared, cultivated for a short time, and then allowed to 

 revert to jungle, or as too frequently happens, to become invaded 

 by the rank "lalang" grass (Imperata arundinacea and Saccharum 

 spontaneum), which prevents the forest getting a foothold, and 

 renders the land quite useless for cultivation. 



The lowland forests have largely disappeared, and one must 

 usually go to the mountains to see the primaeval forest. As in 

 the Malay States, the great development of rubber plantations has 

 been largely responsible for the destruction of the original forests. 



Forbes 2 gives an interesting account of the flora of one of the 



1 Forbes, H. O., A Naturalist's Wanderings in the Eastern Archipelago, p. 221, 

 1885. 



2 Loc. cit., p. 206. 



