Why do cacti have needles?

In its native habitat, the needles of a cactus protect it from animals that attempt to scavenge water from the plant. The needles are more efficient than leaves at conserving water, as they do not lose water through evaporation.

Cacti have evolved thick, broad stems that are excellent reservoirs of water. Water storage is important in the hot, dry desert environments where cacti live. Cacti produce blooms for a short period of time in the spring. New stems branch off from the area of the flower bud. Cacti are native to North and South America and are classified as succulents.