The best-known xeric plant is the cactus, in the family Cactaceae. Cacti perform CAM photosynthesis and are characterized by their strange shapes and prickly thorns. But not all plants that fit this very basic description are cacti!
Here’s a better way to narrow down if you are actually looking at a cactus:
- Thorns will appear in whorled clusters called areoles. These spikes are actually modified leaves that are used for protection rather than photosynthesis. In cacti, leaves can serve a different purpose as the photosynthetic tissue (green tissue) is along the stems and branches of most cacti species.
- Flowers are usually very colorful (red, yellow, pink, etc.), have many petals, and many anthers surrounding the flower center.
- If damaged, the cacti will exude a clear jelly-like sap.
- Cacti grow natively in the western hemisphere in the United States, Mexico, Central America and northern South America. (The one exception to this geographic rule is the genus Rhipsalis. In addition to being found in the New World tropics, some species are native to tropical Africa, Madagascar, and Sri Lanka, probably transported by migrating birds.)