166 COLONIAL REPORTS MISCELLANEOUS. 



shadowed by the very much more powerful action exercised on 

 the vegetation by the copious rainfall. 



M-etamorphic rocks of a granitoid and schistose character, 

 together with frequent outcrops of sandstone and quartz, form 

 the chief materials composing the more important hill ranges ; 

 in the hinterland, where the rainfall is small or a pronounced 

 dry season occurs, the vegetation is much modified by the 

 presence or absence of the different soils due to the weathering 

 of the above rocks. Here, again, laterite reappears as extensive 

 outcrops of a hard, stony, porous character, containing vitreous 

 or cellular concretions of ferric oxide or ferric hydrate, and 

 exercises a profound influence on the plant growth. Its presence 

 is always associated with poor, gnarled, stunted vegetation, 

 exhibiting a very marked xerophilous character. 



The sandj- soil along the sea coast in the vicinity of Accra, 

 for a considerable distance inland from the shore, is much 

 impregnated with salt, which is blown up with the spray and 

 carried a good way in by the strong sea breezes so prevalent in 

 that locality. The vegetation about here, especially that of a 

 shrubby or herbaceous character, has acquired the halophytic 

 habit. 



The Influence of Climate on Vegetation. 



Before dealing with the distribution of the various types of 

 forest to be met with on the Gold Coas., it will be convenient, 

 and it will help to explain the reasons governing this distribution, 

 if a brief description of the reactions on plant life of the climatic 

 and other factors of the environment is given here. 



The flora of the Gold Coast belongs to the zone known as the 

 Tropical Zone, but the local distribution of the various types 

 of vegetation found there is determined, within the limits of the 

 zone, by the amount of atmospheric precipitation prevailing in 

 any one locality. According to the degree of precipitation, the 

 areas may be divided up into climatic districts, with each of 

 which is associated a particular type of vegetation ; within the 

 districts, again, variations in the phj-sical and chemical con- 

 stitution of the soil give rise to other modifications due to 

 edaphic influences. 



The districts may be grouped under three climatic types in 

 accordance with the amount of atmospheric precipitation experi- 

 enced in each. They are:- 



(a) the Hygrophilous climate. 



(&) the Xerophilous climate, 



(c) the Tropophilous climate, 



TO which correspond the Hygrophilous, Xerophilous, and Tropo- 

 philous types, respectively, of vegetation. 



These modifications are brought about by the conditions known 

 as physiological moistness and dryness. which do not always 

 coincide with physical moistness or dryness. 



Anything that affects the available supply of moisture, so as 

 to bring about this physiological moistness or dryness, is accom- 

 panied by hygrophilous or xerophilous vegetation, as the case 



