49§ 



ZONES AND REGIONS [Pt. Ill, Sect. II 



shrubs, which are usually small ; there are no such tall trees as in many 

 tropical savannahs. In other cases, the grassland is true treeless steppe. 



Grassland is present to only a slight extent in the northern warm- 

 temperate belt. It is usually very dry, and may be better described as 

 semi-desert. In New Mexico and Texas, dry savannah is very extensive ; 

 the mezquit (Prosopis julifera) is the most characteristic species. Accord- 





FlG. 262. Interior of the Eucalyptus-forest in Queensland. From a photograph by Semon. 



ing to the nature of the climate and soil, it sometimes grows as a small tree 

 (Fig. 263), at other times as a shrub scattered about the savannah, or is 

 grouped into open savannah-forests. The gigantic cactus, Cereus giganteus, 

 frequently accompanies it. The so-called Spanish steppe may be better 

 described as desert and semi-desert. 



In contrast with the north temperate zone, the south temperate, in its 

 warm belt, is rich in grassland. In particular grassland is very extensive in 

 the south-eastern parts of the southern continents. 



All these grassland-districts seem to be sufficiently well known in all 

 essential points, as regards the composition of their flora. But how their 

 components are affected by climatic conditions, in what manner their 

 dependence on these conditions finds expression in their forms, how the 

 various members of the community reciprocally influence one another, what 



