Orchid Habitats

Orchid Distribution & Types

Orchids are found on every continent with the exception of the arctic poles. The approximate occurrence of orchid species is given in the figure below, with South America by far having its greater share with over a third of all the world's species being found on that continent.

Orchid Types

Orchid species have adapted to various habitats depending on where in the world they are found. Orchids can also interchange their habitat depending on the circumstances in which they find themselves. For example, an epiphytic seed can land and grow in a well drained but still moist area, like a rock next to a stream, if there is enough moisture to sustain its growth.

Approximately 25% of all orchids are Terrestrial or Ground orchids. They live in soil in different types of habitat (forest floor, grassland, woodland, bogs). Their underground parts (tuberoids) store food reserves to ensure the development of new shoots at the beginning of the next growing season. The bee orchids (Ophrys genus) is a good example of a terrestrial orchid.

Below - Ophrys [Oph.] apifera found across Europe and into the Near East and Northern Africa around the Medditerrean Sea.

The majority (70-75%) of all orchid species are Epiphytic orchids. They live on trunks and branches of shrubs and trees. There is a widespread misconception that orchids are parasitic which is not the case! They receive nutrients from the air and depend on rain and mist for their water supply. They use the host tree to gain greater access to light in the forest canopy.

Phalaenopsis [Phal.] schilleriana is found in the Philippines on Luzon Island and on the eastern shores of adjacent islands. It is found at 0-1500 ft. (0-457 m) growing high on tree trunks and on high branches.

Some orchids (less than 5% of all species)also grow on rock faces, and these are called lithophytes. The leaves of lithophytic orchids are often quite fleshy: and their pseudobulbs (a part of the plant specifically modified for the storage of energy and derived from the part of the stem between two leaf nodes) carry the plant through any prolonged dry spells that might occur. They include the paphiopedilums (slipper orchids) and, perhaps best known of this type, the phragmipediums. Since in nature the lithophytes obtain their nutrients in a similar way to the epiphytes, their culture is the same. In each case, nutrients are washed down the surface of the tree bark, or down the rock face, to be absorbed by the orchids' firmly clinging roots. While some roots remain exposed, others grow into rock cracks and crevices and feed on the natural mycelium (fungal spawn) that exists there. Oncidiums, in particular, often produce dense mats of fine roots for this purpose and they live on rocks where the surface provides a good place for germination and attachment of seedlings. Only a few orchids are exclusively lithophytes, most will also be able to develop as epiphytes or terrestrials.

In the astonishing world of the botany, the saprophytic orchids (~ less than 5% of all species) are different from others because they do not carry chlorophyll. Therefore, they need to find food from the organic matters on the forest floor and through the help of the mycorrhizal fungi. The saprophytic orchids will allow mycorrhizal fungi to live inside the tubers or the roots. Those fungi will emit the enzyme to digest the organic matters and will in turn bring about the nutrition needed for the orchids. Water and sugar from the orchids would be the elements given to the fungi in return. The Western Spotted Coral root (Corallorhiza [Corallz.] maculata) pictured below is found across most of North America growing in moist shady woods on rocky slopes in rich decaying humus and rotten leaves at elevations up to 3700 meters.

And finally there is a least one orchid genus Rhizanthella that lives mostly underground. There are currently three species associated with this genus.

The photograph below is Rhizanthella [Rhi.] gardneri,. also known as Western Underground Orchid, is a plant in the orchid family, discovered in the spring of 1928 in the wheatbelt of Western Australia. The white leafless plant is made up of a fleshy underground storage stem (or tuber), which produces flower heads consisting of around 150 tightly packed, tiny flowers. Unlike any other orchid in Australia, the Western Australian underground orchid remains completely underground for its whole life. Not being able to obtain the sun's energy, it instead feeds on the broom honeymyrtle, a shrub. It is linked to it by a mycorrhizal fungus named Thanatephorus gardneri.

This particular orchid is a myco-heterotroph as it relies completely on the broom honeymyrtle and fungus for its nutrients and carbon dioxide. Having received this from the fungus the plant is then able to convert the water, nutrients and carbon dioxide into the energy needed for growth and maintenance. The plant blooms in May and June and measures 2.5-3 cm (1-1 1⁄4 in). The flower heads contains 8 to 90 small dark maroon flowers.

Rhizanthella gardneri reproduces vegetatively by which it can produce three daughter plants. They also undergo sexual reproduction, and underground insects such as termites and gnats are known to pollinate the flowers attracted by the fragrance. The pollinated flower will then take six months to mature. In all studied flowers these were not dispersed and eventually decayed, thus releasing their seeds. It may be, however, that native marsupials were important dispersal agents, but substantial findings are hard to come by as only 19 mature specimens of the orchid are known to currently exist in the wild and only 300 specimens have been collected to date.