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