Plants that do not root in soil are called epiphytes. Generally, they inhabit the humid jungles of the rain forest, obtaining moisture from the atmosphere, but some epiphytes survive in desert conditions. Any root systems they develop are used for anchoring themselves to their host, which is usually a tree, to create stability so they can turn toward the sunlight or collect moisture. Plants that live on air are not parasitic, but live independently from their host.
There are 20,000 different types of orchids, many of which are epiphytic. Epiphytic orchids are well adapted to the rain forests or high elevation cloud forests of Africa and South America because they have large root systems to hold themselves high in the trees. Also, the leaves have a good water-holding capacity that helps them survive periods of dry weather. They depend on pollinators, such as moths, to help them reproduce. They produce tiny seeds that are spread by the wind. The seeds stick to the branches of other trees where they root and grow. Some epiphytic orchids are drought-tolerant, and they grow on rocks and thin soil in desert areas instead of the damp rain forests.
Epiphytic orchids can grow in filtered sunlight if the roots are anchored in sphagnum moss or bark. Orchid-planting medium is commonly available at nursery centers. The most popular examples of U.S.-grown epiphytic orchids are Brassia and Phalaenopsis.
Almost half of the bromeliads in existence can be considered plants that live on air. These types of bromeliads have a very shallow or nonexistent root system and broad leaves that collect water in the space where they meet the main stem. Epiphytic bromeliads have colorful leaves, and they are also native to rain forests where they can collect water from the humid atmosphere and frequent rains. Many epiphytic bromeliads are adaptable as potted or garden plants that can be raised under controlled conditions.
Some popular examples of epiphytic bromeliads are those known as Aechmea, Billbergia and Tillandsia bromeliads. They are easy to find online, and they grow as epiphyte or mostly epiphyte, depending on the growing conditions.
Epiphytic ferns grow anchored in moss that is in turn attached to trees in tropical rain forests. When it rains, epiphytic ferns draw nutrients from rotting leaves and vegetation that collects at their root base. Examples of epiphytic ferns are the rabbit's foot fern and the staghorn fern. They grow in filtered sunlight anchored in sphagnum moss. They should be soaked with water every two to four days and allowed to dry out, since epiphytic ferns can die from over watering.