ROOTS 
103 
tree trunks buttressed by such roots which extend out over 
and beneath the surface, and divide the area about the tree 
into a series of irregular chambers (see Fig. 100). Some- 
FIG. 99. A screw-pine (Pandanus), from the Indian Ocean regioi 
prominent prop roots put out near the base. 
showing the 
times a stem, either inclined or with a poorly developed 
primary root system, puts out prop roots which support 
it, as in the screw-pine (see Fig. 99). A notable case is 
8 
