Question

Why did desert plants have thorns ?

Answer 1

The hairs and spines that grow ondesert plants help reduce moisture loss by breaking the effects of the wind. They also help to cast small shadows on other desert plants, which can protect them from the sun. The hairs and spines can even serve to reflect the sun's rays away from plantsbecause of their shininess.

Answer 2

To reduce the use of water the leaves of cactus are modified into thorns.