Many are savanna grasses, in various parts of the tropics, for instance the large genus Andropogon, Elionurus and others.
On the hills the baobab and hyphaene palm are characteristic; on the plateau are stretches of open savanna, and park-like country with clumps of silk cotton and shea-butter trees.
Agriculture, too, flourishes in the eastern highlands, and throughout the greater part of the steppe and savanna region of the northern and southern zones, especially the latter.
Isolated tufts or tussocks are also characteristic of steppe - and savanna - vegetation and open places generally in the warmer parts of the earth.
The city is built on a comparatively level pajonal or savanna, extending southward from the base of three low hills, called Los Cerros de la Cruz, between the river and the partially filled waters of the Estero Salado.
The dense forests of West Africa contain, in addition to a great variety of dicotyledonous trees, two palms, the Elaeis guincensis (oil-palm) and Raphia vinifera (bamboo-palm), not found, generally speaking, in the savanna regions.
Elionurus, a widespread savanna grass in tropical and subtropical America, and also in the tropics of the old world, is rejected by cattle probably on account of its aromatic character, the spikelets having a strong balsam-like smell.
The more humid regions have a richer vegetation - dense forest where the rainfall is greatest and variations of temperature least, conditions found chiefly on the tropical coasts, and in the west African equatorial basin with its extension towards the upper Nile; and savanna interspersed with trees on the greater part of the plateaus, passing as the desert regions are appNoached into a scrub vegetation consisting of thorny acacias, &c. Forests also occur on the humid slopes of mountain ranges up to a certain elevation.
Where the forest thins to the savanna and steppe, and communication is easier, are found the larger kingdoms and " empires " such as, in the north those established by the Songhai, Hausa, Fula, Bagirmi, Ba-Hima, &c., and in the south the states of Lunda, Kazembe, the Ba-Rotse, &c.