Amaranthus tuberculatus (Moq.) Sauer
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Species Description - Dioecious; prostrate to erect, to 2 m; lvs and infls highly variable; bracts 1–1.5 mm, with slender, strongly excurrent midvein; male fls with 5 subequal sep 2.5–3 mm, the outer acuminate, the inner obtuse or emarginate, the midvein not excurrent; female fls usually without perianth, occasionally with 1 or 2 vestigial sep under 1 mm; fr 1.5–2 mm, indehiscent or bursting irregularly, smooth or roughened; style branches 3 or 4; seeds 0.8–1 mm, lenticular to obovoid, dark reddish-brown; 2n=32. Margins of fresh water; Vt. to N.D., s. to N.J., O., Tenn., La. and Kans. (A. ambigens; Acnida altissima; Acnida subnuda)