226 PLANT RELATIONS. 



spoken of as ''chaparral." These chaparrals are nota- 

 bly composed of mesqnit bushes, acacias and mimosas of 

 various sorts, and other plants. Similar thickets in Af- 

 rica and Australia are frequently sf)oken of as " bush " or 

 "scrub." In all of these cases the thicket has the same 

 general type, and probably represents one of the most for- 

 bidding areas for travel. 



160. Forests, — The xerophyte forest societies may be 

 roughly characterized under three general heads : 



(1) Co niferd us forests. — These forests are very common 

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

 sterile regions towards the south (see Figs. 102, 193, 1!)1). 

 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 largelj'- composed of perennial 

 jjlauts. ^lany 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 subtropi>'al 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 nut so 

 narrow as the needles of conifei's, but are generally lance- 

 shajDed, and stiff and leathery, indicating heavy walls to 

 reduce transpiration. 



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



