Cactus, the common name for a family of desert plants. The plural is cacti or cactuses. Most species bear sharp, needlelike spines, which protect the plants from foraging desert animals. Cacti are famed for their ability to resist drought, which they owe to the fact that moisture from inside the plant evaporates very slowly through the plant’s skin. stems may be globular, cylindrical, branched, trailing and vinelike, ribbed, grooved, or knob-bearing. Only two species have true leaves. The rest of the 2,000 species are leafless.This slender-stemmed cactus from Bolivia and Argentina grows up to 6′. The Firecracker Cactus produces sharp spines and bright orange, flame-like, tubular flowers. The species is easy to cultivate and flower. Cleistocacti are happy with a little extra warmth and water in winter. The orange flowers are unusual. Easy house plant!