The Stinging Nettle, Urtica dioica L., is one of a well known group whose stinging hairs secrete a poison that causes burning and itching inflammation of the skin. It is found from the Atlantic to the prairies. It is an erect plant with thin, ovate, toothed, sharp-pointed leaves, cordate at the base, and with long petioles. The flowers, in large clusters, are either staminate or pistillate. The stem and leaves are provided with stinging hairs.

The Slender Nettle, Urtica gracilis Ait., produces the same effect. It is from two to seven feet high and rarely branched. The leaves are more slender than in Urtica dioica and are not cordate at the base. The Western Nettle, Urtica Lyallii Wats., The Smallest Stinging Nettle, Urtica wrens L., and The Wood Nettle. Laportea canadensis (L.) Gaud., produce similar results.

The juice of the Jewel Weed, Impatiens biflora Walt. gives relief from the inflammation caused by Nettles. The plant is three feet or more tall, grows plentifully in moist places, and is easily recognized by its translucently yellowish-green stem and sac-like, pendent, orange flowers spotted with brown. Relief is obtained by rubbing the crushed stem on the inflamed area, sometimes an enormous reduction of swelling following its application.

Fig. 81.   Slender Nettle

Fig. 81. - Slender Nettle - Urtica gracilis.