General Discussion & Chat: What is the purpose of a thorn?, 1 by Kelli

Kelli wrote:
A lot of plants that live in the desert have thorns. That is because life in the desert is hard enough without having animals munching on you. They say that the spines of a cactus, besides providing protection from grazers, may also provide some shade and reduce the speed of drying winds.

The spines on cholla cactus allow the joints to stick to the fur of passing animals and then the joint is deposited elsewhere where it may root and grow a new plant. Most chollas don't reproduce by seed very well.

This is a picture of a silver cholla, which looks very well proctected and shaded.