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| Elephant grass |
The savanna hosts a range of vegetation, these plants however have adapted to survive in this varying wet and dry humid climate.
In the wetter areas, tall coarse grasses known as elephant grass can be found among many deciduous trees (these trees lose their leaves in the dry season). This is known as the tree savanna. In the drier areas, shorter tufts of grass grow known as tussock grass. This grass is usually accompanied by two types of drought resistant trees, the baobab and the acacia.
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| Tussock grass |
The baobab tree – Also known as the ‘upside-down tree’ has a thick spongy trunk, long tap roots and bears leaves for only a few weeks.
The acacia tree – These have a crown structure, often flattened by the trade winds. These trees lose their leaves in the dry season.
These trees are pyrophytic meaning they can withstand fire mainly due to their insulating bark. They also have leathery leaves to reduce transpiration losses. Other plants are microphyllous, meaning they are small leaved to also reduce transpiration losses.
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| Acacia tree |
In the tree savanna a so-called ‘parkland’ exists. The trees crown shaped tops shade the root areas and help prevent soil moisture evaporation. These trees show xerophytic characteristics meaning they have adapted to survive in dry environments that lack water. These characteristics include:
- Dense cell fluids
- Hard waxy leaves
- Thorns
- A protected stomata
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| Baobab tree |
These all help reduce water loss.
Outside the tree savanna is the grassland savanna where the grasses between the trees become shorter and sparser. The grass tends to die back in the dry season and regrow from root nodules when it rains. Beyond the grassland savanna, is the shrub (scrub) savanna. Here you can find short tufted grasses, acacia trees and thorn bushes. In the shrub savanna, vegetation compete for water and have the ability to turn their blades away from the sun to reduce water loss.
For a better understanding students can watch the savanna grassland video on BBC Bitesize: http://www.bbc.co.uk/schools/gcsebitesize/geography/ecosystems/savannah_grassland_video.shtml
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