Are Cacti Poisonous?

Identification

• Cacti and their close cousins, succulents, are an extremely varied group of plants found throughout the world. They are so different from one another that there is no tried and true way to recognize a cactus. Most of us are familiar with the rounded, shell-like appearance that characterizes most cacti, and their most famous trait is the coating of spines that adorns the outsides of the plant.

Poisonous Cacti

• Most cacti are not poisonous, or they would not be such popular houseplants and garden choices. However, there are a few that contain mildly toxic elements. One such is the prickly pear cactus (Opuntia compressa), which grows in U.S. Department of Agriculture plant hardiness zones 4 through 9. Although this cactus is often enjoyed for its fruit, the small hairs on its stems can irritate skin, eyes and insides.

Nonpoisonous Cacti

• Most cacti are nonpoisonous, unlike their cousins the succulents, which boast a number of toxic plants. Although many cacti contain alkaloids that render them bitter and inedible, very few contain even the mild toxins described above. Mainly they depend on their spines for defense and their prodigious ability to store water in order to stay alive in their harsh, arid natural environments.

Garden Uses

• In addition to their extreme popularity as houseplants, owing to their low-maintenance and drought-resistant natures, cacti are excellent additions to gardens, largely for the same reasons. Once naturalized, they become extremely self-sufficient, only needing watering during the very hottest months and often needing none during cooler winter temperatures. They are good as statement pieces, in knot gardens, and grown in containers.