Quiver Trees

That's what those odd looking desert trees are called... Because the San people (Kalahari bushmen) sometimes used the hollow limb of this tree as a light weight but strong carrying case for their arrows.
The trees have only a thin external layer of hard "wood" and the inner parts a fibrous and pulpy allowing the trees to store water when it becomes available in the rare form of rain...
I took some more pictures .

These trees can survive in some amazingly arid country...

 

And some more pictures of the trees themselves...

Some other plants that live in the same place... amazing adaptations.

This one looks and feels like a ball of spines... I don't know how any animal would be able to eat it!

Some succulents:

And an insect or two from the area: