epiphytic

Epiphytic refers to a growth form in which a plant grows on the surface of another plant, usually a tree, for physical support. Epiphytes are not parasitic; they do not derive water or nutrients from their host. Instead they obtain moisture, nutrients, and light primarily from the atmosphere, rain, dust, and debris that accumulate on the host surface. This lifestyle is common in tropical and subtropical forests, especially in the canopy, but it also occurs in temperate regions and on rocks.

Epiphytes include vascular plants such as orchids, bromeliads, and ferns, as well as non-vascular plants like mosses and liverworts, and even some lichens. Notable examples are epiphytic orchids (Dendrobium, Pleurothallis), bromeliads such as Tillandsia and Guzmania, and non-vascular colonizers such as Tillandsia usneoides (Spanish moss). Adaptations include aerial roots with velamen for moisture uptake, leaf trichomes that trap water and dust, and storage tissues that conserve water. Some clades use CAM photosynthesis to conserve water.

In ecosystems, epiphytes contribute to biodiversity and create microhabitats; bromeliad tanks hold water for various organisms, and epiphytic mats host invertebrates and microorganisms. Heavy epiphytic loads can shade bark or add weight, potentially stressing hosts.

Epiphytism has evolved multiple times across plant groups and is especially diverse in tropical forests. Threats include deforestation, air pollution, and climate change, which can disrupt moisture and nutrient supply. Conservation of intact canopies is crucial for sustaining epiphytic diversity.