The word savanna comes from a Panamanian word for prairie or plains. They are covered with tall grasses. They may have scattered bushes and trees, but not enough to keep grasses from growing.
One common example of a savanna is the tropical grassland, in Africa. They have seasonal rains and dry periods. All savanna plants and trees can survive periods of drought.[1] During the dry season the animals migrate north to countries on the East coast. Until the 20th century the elephant herds moving up the East coast were in the tens of thousands. They are far fewer today.
Some savannas get enough rain to support a forest, but the forest never happens because grazing keeps the trees from growing. Instead, there is lots of grasses and other plants that can regrow from the roots.[2]