They are mostly native to the tropics. The Phalaenopsis and Cattleya genera belong to this group. Lithophytic orchids grow in cracks in rocks. The Laelia genus includes some species with this growth habit. Orchids may also be classified according to their pattern of growth .
Sympodial orchids produce new shoots from the base of old ones.
They develop pseudobulbs , i.e. thickened parts of their stems for storing water and nutrients. These structures allow the plant to become dormant during periods of drought. The Cymbidium and Cattleya genera belong to this category. Monopodial orchids continue to grow each year from existing stems. These orchids do not produce any pseudobulbs.