Trees or shrubs, rarely herbs; leaves generally foliaceous; flowers regular, gamopetalous, usually bell-shaped or urn-shaped; anthers two-celled, with porous dehiscence. A large order, with leaves astringent and bitter, because of the presence of glucosides. Some species contain a poisonous principle, andromedotoxin.
A Manual of Organic Materia Medica and Pharmacognosy, 1917, was written by Lucius E. Sayre, B.S. Ph. M.