It has long, tough spines. The Engelmann's prickly pear is easily identified because of its large, circular or oval stems. The fruit is pear-shaped. The saguaro may have as many as a dozen armlike branches. The importance of cactuses.
Cactuses are important to animals and people.
Small animals, insects, and birds feed on the stems and flowers of cactuses. Many birds build nests in cactus stems. Certain woodpeckers live inside the larger species. Birds and animals may hide from enemies in the stems of a cactus plant. Cactuses also provide food for people.