They are usually classified as warm growing, temperate or cool growing varieties. Orchids are generally grouped as either terrestrial or epiphytic. Terrestrial means growing on the ground. Terrestrial orchids are usually found in marshes, forest floors and grasslands in many tropical and sub-tropical countries. Many of these plants have creeping rhizomes or root-like stems.
Lithophytes grow on rocks.
Epiphytes develop aerial roots allowing them to attach to tree trunks and absorb nutrients. Some of the epiphytic species develop pseudobulbs to store water and food. Phalaenopsis and vandas are examples of monopodial orchids. Monopodials grow from a main stem and grow upward. They have unlimited growth and produce leaves from the stem center.