XEROPHYTE ASSOCIATIONS. 227 



spoken of as " chaparral." These chaparrals are notably 

 composed of mesquit bushes, acacias and mimosas of vari- 

 ous sorts, and other plant.-. Similar thickets in Africa and 

 Australia are frequently spoken of as "bush" or " scrub." 

 In all of these cases the thicket has the same general type, 

 and probably represents one of the most forbidding areas 

 for travel. 



163. Forests. — The xerophyte forest associations may be 

 roughly characterized under three general heads : 



(1) Coniferous forests. — These forests are very common 

 in xerophyte conditions to the north, and also in the more 

 sterile regions towards the south (see Figs. 198 to 201). 

 They are generally spoken of as evergreen forests, although 

 the name is not distinctive. These forests are of several 

 types, such as true pine forests, in which pines are the 

 prevailing trees and the shade is not dense ; the fir and 

 hemlock forests, which are relatively dark ; and the mixed 

 forests, in which there is a mingling of various conifers. 

 In such forests the soil is often very bare, and such under- 

 growth as does occur is largely composed of perennial 

 plants. Many characteristic shrubs with fleshy fruits oc- 

 cur, such as huckleberries, bearberries, junipers, etc. It 

 will be noted that in these forests a characteristic adapta- 

 tion to xerophyte conditions is the development of needle 

 leaves, which are not only narrow, thus presenting a small 

 exposure of surface, but also have heavy walls, which 

 further prevents excessive transpiration. 



(2) Foliage forests. — These are more characteristic of 

 tropical and subtropical xerophyte regions. Illustrations 

 may be obtained from the eucalyptus, a characteristic 

 Australian forest tree, the live oaks, oleanders, etc. It 

 will be noticed that in these cases the leaves are not so 

 narrow as the needles of conifers, but are generally lance- 

 shaped, and stiff and leathery, indicating heavy walls to 

 reduce transpiration. 



(3) Leafless forests. — In Java and other oriental regions 



