A combination of the above defenses
They have thorns
They have toxic chemicals
Ants protect them
They avoid each other as much as possible
They all migrate in different directions
Their territories don't overlap
They eat different foods
Developing fire-resistant cover
Having deep roots
All of the above
Growing quickly
Winter and fall
Winter and summer
Spring and summer
Dry and wet
North America
Asia
Australia
Antarctica
Desert
Grassland
Tundra
Temperate forest
The savanna gets a fair amount of rain, at least 20 inches a year.