a. Pertaining to, or resembling, a natural order
(Orchidaceae) of endogenous plants of which the genus Orchis is the
type. They are mostly perennial herbs having the stamens and pistils
united in a single column, and normally three petals and three sepals,
all adherent to the ovary. The flowers are curiously shaped, often
resembling insects, the odd or lower petal (called the lip) being
unlike the others, and sometimes of a strange and unexpected
appearance. About one hundred species occur in the United States, but
several thousand in the tropics.
