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cactus
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Acactus(plural:cacti,cactuses, orcactus)[3]is a member of theplantfamilyCactaceaewithin the orderCaryophyllales. The word "cactus" derives, through Latin, from theAncient Greek,kaktos, a name originally used byTheophrastusfor a spiny plant whose identity is not certain.[4]Cacti occur in a wide range of shapes and sizes. Most cacti live in habitats subject to at least some drought. Many live in extremely dry environments, even being found in theAtacama Desert, one of the driest places on earth. Cacti show many adaptations to conserve water. Almost all cacti aresucculents. Unlike many othersucculents, the stem is the only part of most cacti where this vital process takes place. Cactus stems store water. Most species of cacti have lost true leaves, retaining onlyspines, which are highly modified leaves. As well as defending againstherbivores, spines help prevent water loss by reducing air flow close to the cactus and providing some shade. In the absence of leaves, enlargedstemscarry outphotosynthesis. Cacti are native to the Americas, ranging fromPatagoniain the south to parts of westernCanadain the northexcept forRhipsalis baccifera, which also grows inAfricaandSri Lanka.