An epiphytic plant grows on the surface of another plant for physical support, not sustenance. These plants, often called “air plants,” are not parasitic and do not draw nutrients from their host. They anchor themselves to tree trunks or branches to access sunlight and moisture in dense forests.
How Epiphytes Survive Without Soil
Living without a connection to the ground requires specialized adaptations for acquiring water and nutrients. Epiphytes absorb moisture from rain, fog, and ambient humidity. Nutrients are derived from atmospheric dust and the organic debris that accumulates around them.
Many epiphytes possess specialized aerial roots that serve distinct functions. Some roots are primarily for anchoring the plant firmly to its host. Others are adapted for absorption; orchid roots, for example, are covered in a spongy, multi-layered tissue called velamen. This structure rapidly soaks up atmospheric moisture and protects the inner root from drying out.
Other epiphytes have evolved unique leaf structures to capture and store resources. Bromeliads, for instance, often have leaves that grow in a tight, overlapping rosette, forming a central “tank.” This cup-like structure collects rainwater, falling leaves, and other organic debris. This mixture decomposes, creating a nutrient-rich liquid that the plant can absorb directly through specialized leaf bases.
In plants like Spanish moss, the leaves are covered in highly efficient absorptive structures called trichomes. These tiny, scale-like hairs cover the plant’s surface and are capable of capturing water and dissolved minerals directly from the atmosphere. When it rains or is foggy, these trichomes swell and hold moisture, allowing the plant to sustain itself.
Common Epiphytic Plants
A wide variety of plants across different families have adopted an epiphytic lifestyle. Orchids are one of the most well-known groups, with thousands of species that grow on trees in tropical and subtropical climates. Their prominent aerial roots, with their spongy velamen covering, cling to bark and absorb moisture from the humid air.
The bromeliad family is another large group containing many epiphytes, including the familiar Tillandsia species, often marketed as “air plants.” This family includes plants like Spanish moss that use trichomes and others, such as Guzmania, that use the tank-forming strategy.
Many fern species also thrive as epiphytes in moist, shaded forests. The Staghorn fern (Platycerium) is a classic example, with unique fronds that collect falling debris to create its own compost pile. Mosses and lichens are also common epiphytes in both temperate and tropical regions.
The Role of Epiphytes in Their Environment
The relationship between an epiphyte and its host is commensal, meaning the epiphyte benefits while the host is unharmed. In rare instances, a dense growth of epiphytes can become heavy when waterlogged, potentially causing branches to break.
Epiphytes are significant contributors to their ecosystems. Their structures create unique microhabitats that provide shelter and water for a vast array of organisms, including insects, spiders, frogs, and bacteria. The water stored in bromeliad tanks, for example, can become a miniature ecosystem in itself.
These plants play a part in the forest’s nutrient and water cycles. They intercept rainfall and capture nutrients from the atmosphere and falling debris that might otherwise be washed away. By retaining moisture, they can create a cooler, more humid microclimate in the host tree’s canopy. Eventually, when epiphytes die and decompose, they contribute to the nutrient litter on the forest floor, enriching the entire system.