An epiphyte is a plant growing on other plants. Epiphytes are known as “air plants” because they are not anchored in the soil. Epiphytes derive nutrients from rainwater, air and from other sources. There are many adaptations present in the epiphytes to get nutrients and survive.
Epiphytes are found on branches, leaves, trunk and other surfaces of plants. Epiphytes anchor themselves to a tree, but do not obtain water or other nutrients directly from it. Epiphytes are commonly found in rainforests.
Epiphytes mostly grow on other plants for physical support and prepare their own food. They obtain adequate light by living on the tree. They get water from the rainwater dripping down from branches and nutrients, that is washed out of leaves during rainfall. Epiphytes derive nutrients from the dead and decaying plant parts present around the surface.
This type of biological interaction is known as commensalism. In Commensalism, one of the species gets benefited and the other species is neither benefited nor harmed. They usually don’t harm their host. But some epiphytes compete with their host for light and nutrients and harm them.
Epiphytes Adaptations and Characteristics
Epiphytes are well adapted to suit their requirements. There is a shortage of water and nutrients at the canopy of the forest, to overcome these, epiphytes are well adapted to capture the nutrients and water present in the air, from the debris of trees and rain. Adaptations of epiphytes help them grow in the area where the ground is populated by many plants.
- Epiphytes generally grow in the densely populated rainforests, where there is too much competition to get light, water, nutrients, etc. Their epiphytic habit helps them to get light and get benefited from the air rich in moisture.
- Epiphytes are found in both tropical and temperate regions
- Ball moss is present in the coastal desert of Mexico. It gets moisture from fog
- Epiphytes have aerial roots to anchor the plant to the surface they grow
- In some of the epiphytic plants, roots are specialised to perform other functions too, e.g. some of the Orchids have photosynthetic roots and in some plants, roots absorb moisture too
- In a parasitic epiphyte, mistletoe, roots are modified to penetrate the host plant and absorb water
- In Strangler fig, an epiphyte, roots become too long and reach the ground anchoring the plant in the soil. They eventually kill the host tree by growing around it and crushing its secondary phloem. They compete with the host tree for light and other resources.
- Orchids can conserve water in their thick stems
- Certain epiphytes have leaves modified as furrow or pitcher to collect rainwater
- Seeds of epiphytes have wings, parachute or gliding apparatus and sticky coats for easy dispersal
- They make fleshy and edible fruits, seeds get dispersed by animals and birds
- Some epiphytes are very selective in their choice of host plant such as Tortula pagorum, present on the bark of trees, only within the city limits
- Epiphytes contribute to a rich ecosystem. They not only grow on trees, but plants like mosses grow on rocks and moist areas of houses, etc.
Epiphytes can be categorised as:
- Holo-epiphyte: An epiphyte which completes its lifecycle on the host plant without coming on the ground, e.g. Orchids
- Hemi-epiphyte: An epiphyte, which later in its life, reaches the ground. Its root develops and makes contact with the ground, e.g. Strangler fig
- Proto-epiphytes: They are dependent on the host to derive nourishment. They lack adaptive features except for aerial roots, e.g. Peperomia
Epiphytes belong to many plant families such as Bromeliaceae, Orchidaceae, etc. Some of the common epiphytes include mosses, ferns, bromeliads, lichens, liverworts and orchids.
- Orchids: They are found in various shapes, patterns, colours and sizes. They are the largest flowering plants. They are found everywhere except Antarctica, e.g. orchids are present as an epiphyte on a mango branch
- Ferns: They are present in moist areas. The epiphytic ferns include Asplenium (birds nest ferns) and Platycerium
- Bromeliad: They are well-known epiphytes of the Bromeliaceae family. Many bromeliads have their leaves overlap each other to store rainwater. In Tillandsia, water is gathered by trichomes
- Epiphytic Cacti: Epiphytic cacti grow in rainforests. They anchor tree branches with their roots and collect organic decomposed water