Wild rice plant description
Two species of plant are commonly known as wild rice. One of them (Zizania aquatica L.) has narrow leaves; rather short, compact flower clusters averaging about 16 inces in length; and stems that seldom exceed 8 feet in hight. It is also often distinguished by purple male and female flowers with leaf markings of the same color. The other species (Z. palustris L.) has broad leaves; rather long, losse flower clusters, varying in length from 15 to 29 inches and stems that range in height from 7 to 11 feet. Purple flowers and leaves are not characteristic of this species, though individual plants often are so marked.
Charles E. Chambliss, Wild Rice (Washington, D.C.: U.S. Dept. of Agriculture, Circular 229, 1922), 4-5.