Most of the orchids are:
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.
The majority of epiphytic plants are angiosperms (flowering plants); they include many species of orchids, tillandsias, and other members of the pineapple family (Bromeliaceae). Mosses, ferns, and liverworts are also common epiphytes and are found in both tropical and temperate regions.