Types of Cactus
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Most of the 2000 known species are native to North, Central and South America, and the vast majority of cacti, but not all, are well adapted to desert conditions, using their stems to store water during extended dry seasons.
Cacti are also flowering plants that serve an important role in their ecosystem by providing food and shelter to many animals, birds and reptiles. Desert tortoises, for example, often snack on their local cactus stems and fruits.
| Types of Cactus Garden Cactus Large Cactus Types of Flowers |
Human attraction to cacti rivals that of wildlife. They are big business in America, selling as ornamental plants for homes and gardens as well as selling in a variety of consumer products from jam to cosmetics.
Trade in cacti has also greatly expanded in the past couple of decades. The Convention on International Trade in Endangered Species (CITES) lists over one hundred cacti species in Appendix I, meaning trade is prohibited. (see Trade in Chihuahuan Desert Cacti).
Prickly pear cactus, genus Opuntia, rank as most common genus of native North American cacti.
Approximately two dozen species have been identified, ranging in size from one to six feet in height. Depending on the species, spines might cover their flat pads (leaves).
While most species adapt to the dry, desert Southwest climates, some prickly pear species extend their range across multiple climate zones. The U.S. Forest Service, for example, lists thirty five separate states that host the Eastern Prickly Pear Cactus (Opuntia humifusa).
Apart from sharing the common physical trait of flat leaves, differences among Opuntia species make them rather easily identified. Their pads and spines also tend to show characteristic coloring based on species type.
The top picture shows the flower of the Texas Prickly Pear Cactus. The bottom picture shows a new Texas Prickly pear leaf.
The Beavertail cactus (Opuntia basilaris), a related species with flat pads, grows between one and two feet tall.
Unlike other prickly pear species, it lacks spines on the pads. Absent the spines, it produces glochids, or small sharp hair-like features, as a defense mechanism. They can stick as sharply as any spine.
Beavertail cacti grow at different altitudes, in the sandy soils of the desert Southwest.
The largest cactus, the Saguaro, can grow up to sixty feet tall. Pincushion cactus, on the other hand, usually grow no more than a few inches above the ground.
The links in the right box point to articles covering the smaller cactus species suited for North American gardens and a few examples of the larger North American cactus plants.
© 2004-2012 Patricia A. Michaels