1G0 OUTLINE OF PLANT GEOGRAPHY 



From the Niger delta to the Congo, the mangrove swamps 

 are developed od an enormous scale. 



The Wesl African rain-forest reaches its greatest develop- 

 ment in Kamerun, where rich volcanic soils combine with an 

 equatorial climate to produce a maximum luxuriance of vegeta- 

 tion; but the whole coastal region from the Niger to the Congo 

 has a very heavy forest. 



The country rises rapidly back of the coast, and the forest 

 is largely restricted to the regions bordering the great rivers 

 which descend from the interior, while much of the inland country 

 is open grass-land or savanna. 



Back of the coastal belt of mangroves is a strip of " alluvial 

 forest," composed of a variety of trees, shrubs, and climbing 

 plants, but having only trees of moderate size. 



Almost the first tree to invade the new land, is a screw-pine 

 (Pandanus candelabrum). The screw-pines are all palaeotropic, 

 and are very characteristic of the strand floras, although by 

 no means restricted to the coastal regions. Their curious stilt- 

 like roots and spirally set sword-shaped leaves are a familiar 

 sight in the tropics of the old world, and they are not uncom- 

 mon in cultivation. 



Several species of palms are characteristic of the alluvial forest. 

 Among these are a wild date (Phoenix spinosa) and the wine- 

 palm {Raphia vinifera), as well as rattan-palms, climbing species, 

 whose thorny stems and leaves are a terror to the explorer. With 

 these are associated species of low-growing trees and shrubs, 

 belonging to many families, but with Leguminosae most abun- 

 dant. Climbing plants of many sorts abound, as they do every- 

 where where light is sufficient. 



Characteristic of the whole coastal zone is the oil-palm (Elaeis 

 Guieneensis) , which grows wild, but is also extensively planted. 

 This yields the palm-oil, such an important article of commerce. 

 The oil-palm is a very handsome tree, often seen in cultivation 

 in tropical countries. It has enormous feathery leaves, and 

 the persistent leaf-bases, and rough stem offer a very favorable 

 attachment for orchids, ferns and other epiphytes. 



The alluvial, or border forest, passes gradually into the high 

 rain-forest in which the variety of trees is very great, and many 

 of them attain gigantic size. The trees are very tall, and the 



