An epiphyte (from Ancient Greek epi-, meaning 'upon', and phutón, meaning 'plant') is a plant or plant-like organism that grows on the surface of another plant or plant-like organism such as kelp. It derives its moisture and nutrients from the air, rain, water (in marine environments) or from debris accumulating around it. The plants on which epiphytes grow are called phorophytes. Epiphytes take part in nutrient cycles and add to both the diversity and biomass of the ecosystem in which they occur, like any other organism. In some cases, a rainforest tree's epiphytes may weigh several tonnes. Epiphytes differ from parasitic plants in that they grow on the host for physical support only, and do not draw nourishment from it. An organism that grows on another organism that is not a plant may be 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 Greek epi- 'upon' and phyton 'plant'. Epiphytic plants are sometimes called "air plants" because they do not root in soil. However, that term is inaccurate, as there are many aquatic species of algae that are epiphytes on other aquatic plants (seaweeds or aquatic angiosperms).