The African savanna is a vast, rolling grassland primarily found in the southeastern part of the continent. It is a tertiary ecosystem, meaning that it is found between tropical and desert landscapes, featuring mainly shrubs and isolated trees. Although plant life in the savanna is mainly restricted to grass, shrubs and trees, it is remarkably diverse and features many different species.
Although the savanna is defined as a grassland, several species of tree dot the landscape. The most common varieties are members of the acacia genus (Acacia), and include Senegal acacia (A. senegal) and umbrella thorn acacia (A. tortilis). Both species are recognizable for their flat-topped shape and thorny branches. Jackal berry tree (Diospyros mespiliformus) is another common savanna species, and is among the tallest trees in the ecosystem, reaching a height of 80 feet. Although less common, the candelabra tree (Euphorbia ingens) is often seen near the edges of the savanna. It is an unusual tree with erect, upward-pointing branches that resemble cacti. It contains milky, latex-like sap known to burn skin and cause blindness.
Shrubs generally occur within the savanna near sources of water and along the slopes of hills. Sickle Bush (Dichrostachys cinerea) is one of the most common shrubs in the savanna, found along brackish waterways and in roadside ditches. It is a small, densely matted bush growing to 6 feet in height with feathery foliage and spiny branches. Several species of raisin bush (Grewia) are also commonly found near seasonal and permanent watersheds in the savanna. White raisin bush (G. bicolor) is identifiable by its large, hairy leaves and yellow, star-shaped flowers. It is named for its fruit, which resemble reddish-brown raisins when ripe. Sandpaper raisin (G. flavescens) superficially resembles other members of the genus, although its fruit ripens later in the year, from March until July. Buffalo thorn (Ziziphus mucronata) is a large shrub known for its distinctive zig-zag shaped twigs and shiny, light-green leaves. It is found in sandy soil and open woodland, as well as along seasonal riverbeds.
By far the most abundant type of plant in the savanna, grasses define the ecosystem and represent nearly 75 species, states Bryan Shorocks in his book "The Biology of African Savannas." Common finger grass (Digitaria eriantha) is the African savanna's most important forage grass. Animals rely on the long-lived foliage through the dry season when most other types of grass become unpalatable. It is easily recognizable by the finger-like flowering tufts that top each stem. Eleven species of lovegrass (Eragrostis) are also commonly found throughout the savanna. Of those, saw-tooth lovegrass (E. superba) and heart seed lovegrass (E. capensis) are the most abundant. Bluestem grass (Bothriochloa) is found in the warmer areas of the savanna, and include three common species: purple plume grass (B. bladhii), pinhole grass (B. insculpta) and stinking grass (B. radicans).