THE FERTILITY OF SOILS IN THE TROPICS 421 



tressed type predominates. A very stiff clay, such as is 

 occasionally met with, may support trees only a few inches 

 in diameter. Swampy lands along the coast usually grow 

 species of mangrove, inland swamps mangrove also, 

 Pandanus spp. and Nipa fruticans. Bamboo growth 

 is an indication of good texture; but where the asso- 

 ciated undergrowth is scanty and of a fibrous nature, 

 such as small palms, the soil is probably too sandy to 

 be fertile. Extreme infertility, either on sand or clay, 

 is denoted by the presence of species of Nepenthes, the 

 insectivorous " pitcher plant." 



