The three sepals are the outermost elements. Certain genera show structural modification in the sepals and may be partially or totally fused to make a single floral part .There are also three petals, the two laterals ones being symmeterical and almost always simple in form, the central one modified into the labellum and lip. The lip is a complex and variable flower structure with the function of attracting insects and guiding them for pollination. The distinctive structure of the lip is also used for variety identification. In the majority of the genus the leaves have parallel veins , a characteristic of the monocotyledons.
Some genus have a thick and succulent leaves while others have thin and papery leaves.
The leaves of commerciallly grown orchids in Malaysia show a succulent appearance and function as a genuine storage organ except those of the Oncidiums which has thin leaves. The Root Simpodial orchids such as the Oncidiums and Dendrobiums have only a fibrous root system while the monopodiums would have both fibrous as well as aerial roots. The root are covered with a vital organ called velamen up to a few milimeters at it tips. This tissue can absorb large amount of water very rapidly. It also provides the root with a great deal of protection.