Orchid Distribution & Types
Approximately 25% of all orchids are Terrestrial or Ground orchids. They live in soil in different types of habitat (forest floor, grassland, woodland, bogs). There 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
Right Ophrys [Oph.] apifera found across Europe and into the Near East and Northern Africa around the Medditerrean Sea
Left is 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; they and the 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 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. 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.
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 head 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.
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.