A cactus is a member of the plant family Cactaceae within the order Caryophyllales. Almost all cacti are succulents. The word "cactus" derives, through Latin, from the Ancient Greek κάκÏÎ¿Ï , a name originally used for a spiny plant whose identity is not certain. Cacti are native to the Americas, ranging from Patagonia in the south to parts of western Canada in the northâexcept for Rhipsalis baccifera, which also grows in Africa and Sri Lanka.