Urtica urens - Burning Nettle

Burning Nettle is an annual herb with stems branched, 10-60 cm tall, sparsely finely velvet-hairy and somewhat densely armed with stinging hairs; lower internodes 4-7 cm, upper internodes 1-3 cm. Stipules free, narrowly triangular, 1-2.5 mm, fringed with hairs. Leaf-stalks are 1-2.5 cm, finely velvet-hairy, sparsely armed with stinging hairs. Leaves are broadly elliptic, sometimes ovate or obovate, 1.2-6 x 0.6-3 cm, 5-veined, often nearly hairless except for sparse stinging hairs on both surfaces, base broadly wedge-shaped or rounded, margin 6-11-toothed, tip blunt-rounded; crystalline warts distinct above. Flowers are borne in spikes 0.5-2.5 cm, containing proximal female flowers and distal male flowers. Male flowers are short stalked, in bud about 1.2 mm; tepals fused 1/2 of length, finely velvet-hairy. Female flowers have tepals fused at base, dorsal-ventral lobes ovate, equaling achene, often with 1 stinging hair on dorsal rib, sparsely setulose along margin, lateral lobes ovate, about 5 times as small as others. Seedpods are brownish gray, ovoid, compressed, 0.8 mm, verrucose, invested by persistent tepals. Flowering: May-July.