In West Texas, cactus, grass and trees put down roots in what seems to be solid rock. It's a mystery to some as to how a clump of cactus can thrive in rock. Mystery solved...cacti have a very shallow root system.
Of an even greater intrique is how the mighty Oak can grow and thrive in rock. As you can see, the oak growing out of the Red Rocks is a variety of Oak called ScrubOak. In parts of West Texas there are ScrubOak Forests.