Epiphytes

An epiphyte is a plant that grows harmlessly upon another plant (such as a tree) and derives its moisture and nutrients from the air, rain, and sometimes from debris accumulating around it. Epiphytes differ from parasites in that epiphytes grow on other plants for physical support and do not necessarily negatively affect the host. An epiphytic organism that is not a plant is called an epibiont. Epiphytes are usually found in the temperate zone (e.g., many mosses, liverworts, lichens, and algae) or in the tropics (e.g., many ferns, cacti, orchids, and bromeliads). Epiphyte species make good houseplants due to their minimal water and soil requirements. Epiphytes provide a rich and diverse habitat for other organisms including animals, fungi, bacteria, and myxomycetes.

Epiphyte is one of the subdivisions of the Raunkiær system.

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 epiphytes 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.

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