Cactus (plural: cactus, cactus or cactus) is a member of the family cactus, which includes about 127 genera and about 1750 known species of Caryophyllaceae. The word "cactus" comes from the Latin origin of the ancient Greek KAKTOS. The name was originally used by Theophrastus for the spiny plant with uncertain identity. Cacti come in all shapes and sizes. Most cacti live in habitats that suffer at least drought. Many people live in extremely dry environments, even in the Atacama Desert, one of the driest regions on earth. Cactus shows a variety of water-saving effects. Almost all cacti are succulent plants, which means they have thickened, fleshy parts that can store water. Unlike many other succulent plants, stems are the only part of this important process that occurs in most cacti. Most cactus species have lost their true leaves and only retain thorns, which are highly modified leaves. In addition to defending herbivores, thorns can help prevent water loss by reducing air flow near cacti and providing some shade. In the absence of leaves, stem photosynthesis occurs. Cacti are native to America and range from Patagonia in the south to parts of western Canada in the North (in addition to Indian artichoke flowers in Africa and Sri Lanka).