An epiphyte is a plant that grows upon another plant (such as a tree) non-parasitically or sometimes upon some other object (such as a building or a telegraph wire), derives its moisture and nutrients from the air and rain and sometimes from debris accumulating around it, and is found in the temperate zone (as many mosses, liverworts, lichens and algae) and in the tropics (as many ferns, cacti, orchids, and bromeliads) – also called air plants."
Epiphyte is one of the subdivisions of the Raunkiær system. The term most commonly refers to higher plants, but epiphytic bacteria, fungi (epiphytic fungi), algae, lichens, mosses, and ferns exist as well. The term epiphytic derives from the Greek epi- (meaning 'upon') and phyton (meaning 'plant'). Epiphytic plants are sometimes called "air plants" because they do not root in soil. However, there are many aquatic species of algae, including seaweeds, that are epiphytes on other aquatic plants (seaweeds or aquatic angiosperms).
The best-known epiphytic plants include mosses, orchids, and bromeliads such as Spanish moss (of the genus Tillandsia), but epiphytic plants may be found in every major group of the plant kingdom. 89% of epiphyte species (about 24,000) are flowering plants. The second largest group are the leptosporangiate ferns, with about 2800 species (10% of epiphytes). In fact, about one third of all ferns are epiphytes. The third largest group is clubmosses, with 190 species, followed by a handful of species in each of the spikemosses, other ferns, Gnetales, and cycads.
Epiphytic organisms usually derive only physical support and not nutrition from their host, though they may sometimes damage the host. Parasitic and semiparasitic plants growing on other plants (mistletoe is well known) are not "true" epiphytes (a designation usually given to fully autotrophic epiphytes), but are still epiphytic in habit. Plants such as New Zealand species of Griselinia, which send long roots down towards the soil whilst fixed high in another plant and reliant upon it for physical support, are also epiphytic in habit.
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