Herbs, shrubs, or trees, with opposite, entire leaves connected by stipules or a stipular line, and with regular 4-5-merous, 4-5-androus flowers, the ovary free from the calyx. Many of the plants belonging to this order are extremely poisonous.

A Manual of Organic Materia Medica and Pharmacognosy, 1917, was written by Lucius E. Sayre, B.S. Ph. M.