cactus properly refers to plants belonging to the family Cactaceae. With one exception, all are native to the New World (the Americas). The sole exception is Rhipsalis, a jungle epiphyte found in tropical Africa, Madagascar, and Sri Lanka, as well as North and South America. Informally, cactus is used to refer to any stem succulent adapted to a dry climate, notably species from genus Euphorbia with forms reminiscent of Cactaceae. To be precise, these succulents are correctly described as "cactoid" or "cactiform" unless they are actual members of the Cactaceae.