As well as spines, areoles give rise to flowers, which are usually tubular and multipetaled. Areoles are an identifying feature of cacti. Cacti are native to the Americas, ranging from Patagonia in the south to parts of western Canada in the north-except for Rhipsalis baccifera, which also grows in Africa and Sri Lanka.Ĭactus spines are produced from specialized structures called areoles, a kind of highly reduced branch. In the absence of true leaves, cacti's enlarged stems carry out photosynthesis.

As well as defending against herbivores, spines help prevent water loss by reducing air flow close to the cactus and providing some shade. Most species of cacti have lost true leaves, retaining only spines, which are highly modified leaves. Unlike many other succulents, the stem is the only part of most cacti where this vital process takes place. For example, almost all cacti are succulents, meaning they have thickened, fleshy parts adapted to store water. Because of this, cacti show many adaptations to conserve water. Many live in extremely dry environments, even being found in the Atacama Desert, one of the driest places on Earth. Although some species live in quite humid environments, most cacti live in habitats subject to at least some drought. Cacti occur in a wide range of shapes and sizes. The word cactus derives, through Latin, from the Ancient Greek word κάκτος ( káktos), a name originally used by Theophrastus for a spiny plant whose identity is now not certain. Many species of cactus have long, sharp spines, like this Opuntia.Ī cactus (plural cacti, cactuses, or less commonly, cactus) is a member of the plant family Cactaceae, a family comprising about 127 genera with some 1750 known species of the order Caryophyllales.

Cactus low growing soft thorns