412 



MANUAL OF POISONOUS PLANTS 



Urtica gracilis Ait. 



A perennial from 2-6 feet high, sparingly bristly; leaves ovate, lanceolate 

 with slender petioles; long, accuminate, sharply serrate, 3-S-nerved, the slender 

 petioles sparingly bristly; flowers dioecious or with staminate and pistillate 

 clusters. The stinging hairs of this and other species of the genus contain 

 formic acid. A common weed in dry or moist ground along fence rows 

 from Canada to British Columbia, Kansas and North Carolina. 



Poisonous properties. The nettle and some other plants produce what is 

 commonly called "urticaria" or nettle rash. It is an inflammatory disorder 

 with a burning and itching sensation. It may come out in large or small 

 patches, remaining for a few minutes or several hours and may disappear 

 as abruptly. It usually leaves no trace behind. The nettle is supposed to con- 

 tain an irritant toxic principle, formic acid, but recent studies seem to indi- 

 cate that the urticaria is probably caused by one of the toxins. 



The following species of the genus have urticating properties: Urtica 

 Membranaceae, U. spatulata and U. pilulifera. 



ISO 



189 



Fig. 192. Stinging Nettle (,Vrtica 

 wrens). (From Darlington's Weeds 

 and Useful Plants.) 



Urtica urens L. Small Stinging Nettle 



An annual from 1-2 feet high; stem 4-angled, tough, branching with a 

 few stinging virulent hairs; leaves elliptical or ovate, serrate or incised, with 

 scattered stinging hairs; flowers loose or in racemose spikes; sepals 4 petals 

 4; fruit straight, ovate, flattened achene. 



