Diœcious, perennial from a woody rhizome about 1/4 in. thick; stem erect, woody and rooting below, hollow, 5 lin. or less in thickness, finely pubescent, ultimately becoming glabrous, hirsute, especially in the younger parts, with spreading white stinging hairs, up to 4 ft. high. Leaves petioled, membranous, ovate, apex generally broadly acuminate, base cordate, margin grossly serrate, 5-nerved from the base, the lower pair of nerves weak, 2–3 1/2 in. long, 1 1/2–2 1/2 in. wide, surface obscurely dotted with cystoliths, pubescent and with a few short stinging hairs especially beneath and on the veins; petiole more or less beset with stinging hairs, 1–1 1/2 in. long; stipules free, herbaceous, broadly ovate-triangular, 1/4– 1/3 in. long. Inflorescences erect, longer than the petioles. Female flowers in dense clusters arranged racemosely on the main axis; outer pair of perianth-segments minute, broadly ovate, glabrous, inner pair broadly elliptic, 1/2 lin. long, glabrous, with 1–3 large dorsal stinging hairs. Achene compressed, ovate, pale brown, a little over 1 lin. long, enveloped in the persistent dry membranous inner perianth-segments.