An important order on account of its valuable wood. It is characterized by alternate leaves and monoecious flowers, the sterile ones in catkins, the fertile in clusters or spikes, and the fruit a 1-seeded nut, with or without a woody, scaly involucre (cupule).
A Manual of Organic Materia Medica and Pharmacognosy, 1917, was written by Lucius E. Sayre, B.S. Ph. M.