19 



Zone is the basin of the Volta River and its tributaries flowing in a 

 south-easterly direction. The area of this Zone within the Gold Coast 

 territories therefore presents the features of a periplane drained by 

 the Volta River. 



The chief characteristic of the Sudanese Zone is an open growth 

 of trees, or their entire absence, with a universal covering of grass 

 broken only by the exposures of bare rock. Trees and bushes 

 are generally of the same genera as those found in the Guinea Zone, 

 the fires making tree growth slow and erratic and producing a gnarled 

 and stunted type of tree whose crown is kept low by the wind after 

 it has raised itself above the influence of the fire. The arboreal and 

 fruticose vegetation generally may be considered as one, as it is only 

 when the marsh and aquatic formations are encountered that shrubs 

 appear which are floristically distinct from the trees ; similarly with 

 the herbaceous vegetation which in the drier areas attains a height of 

 three to four feet, or in isolated instances such as the Amorphophallus a 

 little more, but which in the marsh formation may reach 12 or 15 feet 

 in height. The general type of Sudanese vegetation is found on the 

 crests and slopes of the undulations. 



As in the case of the Deciduous Forest some species are identical 

 with those of the Evergreen Forest, such as Afzelia africana; others 

 are found which in the field appear distinct but in the herbarium are 

 difficult to separate. One instance of manj' is that of Lophira alata 

 of this Zone and Lophira procera of the Guinea Zone. From field 

 work one feels justified in considering the xerophytic alata as being 

 directly derived from the hygrophilous procera by being subjected 

 to a prolonged period of fire conditions. This " species " now seems 

 adapted to Sudanese environments, and has assumed a predominance 

 in the Sudanese Zone comparable to the Triplochiton Johnsoni in 

 the Deciduous Forest. 



Economically the forest patches of the Sudanese Zone are valuable 

 as a timber and firewood supply to the inhabitants of the country. 

 Apart from this the most valuable product is the Shea Butter obtained 

 from the fruits of Butyrospermum Parkii. 



The following arboreal species have so far been definitely recorded 

 from the Savannah Forest. 



ARALIACEM. 



Cussonia longissima. 

 BIGNONIACEM. 



Markhamia tomentoso. 



Spathodea campanulata 



CELASTRACEM. 



Gymnosporia sp. 



COMBRETACEM. 



Anogeissus leiocarpa. 



EUPHORBIACEM. 



Aniidesma venosum. 

 Bridelia micrantha. 

 Hymenocardia acida. 

 Uapaca Heudelotii 



