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.
Difficulties and Adaptations for Life in the Savanna
Most savanna regions receive plenty of rainfall, up to 50 inches in some areas. However, the difficulty for plant life is that rain comes in short periods followed by months of drought. Not only does rain fail to fall regularly, but the porous soil doesn't hold moisture well.
In order to compensate for this, savanna plants must have unique adaptations to survive. Many species utilize deep roots to store as much water as possible and reach whatever moisture remains in the soil. They also frequently have features to store water, such as the baobab tree's ability to hold water beneath its bark.
African Savanna Trees
Although the savanna is defined as a grassland, several species of trees dot the landscape. The most common varieties are members of the acacia genus (Acacia spp.), and include Senegal acacia (Acacia 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.
Common Savanna Shrubs
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 six feet in height with feathery foliage and spiny branches.
Several species of raisin bush (Grewia spp.) are also commonly found near seasonal and permanent watersheds in the savanna. White raisin bush (Grewia 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 (Grewia 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.
Grasses of the Savanna
By far the most abundant type of plant in the savanna, grasses define the ecosystem and represent nearly 75 species. 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 spp.) are also commonly found throughout the savanna. Of those, saw-tooth lovegrass (Eragrostis superba) and heart seed lovegrass (E. capensis) are the most abundant. Bluestem grass (Bothriochloa spp.) is found in the warmer areas of the savanna, and include three common species: purple plume grass (Bothriochloa bladhii), pinhole grass (B. insculpta) and stinking grass (B. radicans).
About the Author
Samantha McMullen began writing professionally in 2001. Her nearly 20 years of experience in horticulture informs her work, which has appeared in publications such as Mother Earth News.