They are widely known for their large, showy flowers, and were used extensively in hybridization for the cut-flower trade until quite recently. This genus and the numerous hybrids come close, through their beauty, to the idealized picture we have of the orchids. The flowers of the hybrids can vary in size from 5 cm to 15 cm or more. They occur in all colors except true blue and black.
The typical flower has three rather narrow sepals and three usually broader petals : two petals are similar to each other, and the third is the quite different conspicuous lip, featuring various markings and specks and an often frilly margin. At the base, the margins are folded into a tube. Each flower stalk originates from a pseudobulb. The number of flowers varies; it can be just one or two, or sometimes up to ten. [by Wikipedia]