Epiphytes grow on the surfaces of other plants, most commonly on the trunks and branches of trees in tropical and subtropical forests. They also colonize rocks, cliff faces, and even artificial structures like power lines and fences. Unlike parasites, epiphytes don’t burrow into their host or steal nutrients. They anchor themselves to a surface and pull everything they need, water and minerals, from the air, rain, and organic debris that accumulates around their roots.
Roughly 10% of all vascular plant species on Earth are epiphytes, spread across about 900 genera and 80 families. That includes orchids, ferns, bromeliads, mosses, and lichens. Understanding where they grow means looking at three things: which part of the tree, which type of forest, and which climate conditions make epiphytic life possible.
Vertical Zones on a Host Tree
Epiphytes don’t scatter randomly across a tree. They sort themselves into distinct vertical zones based on how much light, moisture, and wind exposure each spot receives. Researchers divide a host tree into four main zones: the trunk below the first major branch, the inner crown between the first and second branches, the middle crown between the second and third branches, and the outer crown above the third branch.
Ferns tend to cluster in the shaded lower zones, on trunks and lower branches where humidity stays high and direct sunlight is limited. Orchids are more common in the upper canopy, where they receive stronger light on high-strata branches. Mosses and liverworts blanket the lower trunk, especially in cloud forests where moisture is nearly constant. Bromeliads occupy a range of positions depending on species, with smaller “atmospheric” types thriving in exposed upper branches and larger tank-forming species settling in the middle crown where organic debris collects in branch crotches.
Tropical and Cloud Forests
Tropical rainforests hold the greatest concentration of epiphytes on the planet. The combination of warm temperatures, high humidity, and consistent rainfall creates ideal conditions. In cloud forests, where mist regularly envelops the canopy, epiphyte diversity reaches its peak. These forests maintain relative humidity above 95% during parts of the year, and annual rainfall commonly exceeds 2,000 to 3,000 millimeters. In the Kosñipata Valley of the Peruvian Andes, a well-studied cloud forest site, even a drought year still delivered over 3,200 mm of rain.
Cloud immersion is especially critical. Many epiphytes depend on direct contact with fog and mist to maintain their water balance and avoid drying out. When clouds sit at the canopy level, epiphytes absorb moisture through their leaves, roots, or specialized surface structures without needing any rainfall at all. This makes cloud forests uniquely hospitable, and it also makes epiphytes in these ecosystems particularly vulnerable to shifts in cloud patterns.
Temperate Forests
Epiphytes aren’t exclusive to the tropics. Temperate rainforests, particularly in the Pacific Northwest of North America, support rich communities of epiphytic mosses, liverworts, and lichens. In old-growth Douglas fir forests, large lichens in the genus Lobaria are among the most conspicuous epiphytes, draping from branches and trunks. Their abundance increases dramatically with forest age. Old-growth stands support far more epiphytic lichens and bryophytes than younger forests, because older trees develop the complex, layered canopies and thick lateral branches that provide the best growing surfaces.
Broadleaf trees like bigleaf maple are particularly good hosts in these forests, harboring diverse communities of epiphytic mosses on their bark. The key difference from tropical systems is the cast of characters: instead of orchids and bromeliads, temperate epiphyte communities are dominated by non-vascular plants like mosses and lichens that tolerate cooler temperatures and seasonal dry periods.
Dry Tropical Forests
Epiphytes even survive in seasonally dry tropical forests, though the community looks very different. In these habitats, water conservation becomes the defining challenge. Studies from dry forests in Mexico found that 100% of epiphyte species in those environments use a specialized form of photosynthesis called CAM, which allows plants to open their pores for gas exchange only at night, dramatically reducing water loss. In wetter forests, only about 10% of epiphytic species rely on this strategy. Dry forest epiphytes tend to be tough, compact species, often bromeliads and cacti with thick leaves or dense surface hairs that trap moisture from fog and dew.
Rocks and Artificial Structures
Not all epiphytes grow on trees. Lithophytes are closely related in lifestyle but colonize rock surfaces instead of bark. They face similar challenges: anchorage on an impenetrable surface, no access to soil nutrients, and dependence on atmospheric moisture. In practice, the line between a lithophyte and an epiphyte is blurry. Many fern species, like those in the genus Asplenium, grow interchangeably on tree trunks, mossy rocks, and soil banks depending on local conditions. When moss builds up thickly on a rock or a lower tree trunk, the growing conditions become nearly identical regardless of the underlying surface.
Some epiphytes have taken this flexibility further by colonizing human-made structures. In the Americas, bromeliads in the genus Tillandsia are regularly found growing on power lines, fences, and walls. These so-called atmospheric bromeliads account for nearly 95% of all plant observations on power cables. They succeed in these exposed, rootless conditions because their leaves are covered in dense hair-like trichomes that absorb water and nutrients directly from the air. Combined with CAM photosynthesis, this lets them survive on a bare wire with no soil, no bark, and no shade. Larger species like Tillandsia fasciculata and T. elongata also show up on cables, though small atmospheric types dominate.
How Epiphytes Gather Water and Nutrients
Growing without soil requires specialized equipment. Epiphytic orchids have a spongy tissue called velamen coating their roots, which rapidly absorbs water from rain and humid air. Bromeliads take a different approach. Many form a rosette of overlapping leaves that creates a central “tank,” collecting rainwater and fallen debris that slowly decomposes into available nutrients. Their leaves are also covered in absorptive trichomes that pull in water and dissolved minerals not just from rain, but from fog, dew, and even atmospheric gases.
These adaptations explain why epiphytes can thrive in places that seem inhospitable. A bromeliad on a power line or an orchid perched 30 meters up in a canopy gap has no connection to soil, yet its specialized structures let it intercept enough moisture and nutrients from passing air and occasional rain to grow, flower, and reproduce. The substrate matters far less than the atmosphere surrounding it.