326 CONTRIBUTIONS FROM THE NATIONAL. HERBARIUM. 



23. URTICACEAE. Nettle Family. 



1. TTRTICA L. Nettle. 



Perennials, with stinging hairs; leaves opposite, stalked, toothed, with stipules; 

 flowers very small, green, in panicles in the axils of the leaves; sepals 4; petals none; 

 fruit a small green achene. 

 Sterna densely bristly; petioles usually shorter than the breadth of the leaves. 



1. U, dioica. 



Stems with few scattered bristles; petioles usually longer than the breadth of the 



leaves 2. U. lyallii. 



1. Urtica dioica L. Open slopes at east entrance and Belton. Native of Eur.; 

 naturalized in N. Amer. — Stems 30 to 80 cm. high, stout; leaves ovate or heart- 

 shaped, 3 to 10 cm. long, coarsely toothed, 



2. Urtica lyallii S. Wats. Common at low and middle altitudes, in moist woods 

 or thickets; sometimes found above timber line. Alaska to Wash., Wyo., Conn., 

 and Newf. (U. cardiophylla Rydb.; U. viridis Rydb.) — Stems slender, 0.5 to 1.5 

 meters high, nearly glabrous except for the bristles; leaves lance-oblong to ovate 

 or heart-shaped, 5 to 15 cm. long, thin, coarsely toothed. 



The hairs sting the skin very painfully, and their effects sometimes last for 

 several days. 



24. SANTALACEAE. Sandalwood Family. 



1. COMANDRA Nutt. 



1. Comandra pallida A. DC. Bastard toadflax. Common on open rocky slopes 

 or on prairie at low and middle altitudes. B. C. to Man., Ariz., and Tex. — Glabrous 

 perennial, 10 to 30 cm. high; leaves small, alternate, sessile, glaucous, entire; flowers 

 small, white, in cymes; calyx 5-lobed; corolla none; fruit drupelike. 



25. POIYGONACEAE. Buckwheat Family. 



Annual or perennial herbs with alternate leaves (leaves mostly at the base of the 

 stem in some groups); flowers small, with 3 to 6 sepals and no petals; stamens 4 to 8; 

 fruit small, dry, 1-seeded, 3-angled or flattened. 



Leaves without stipules; flowers in small clusters, each cluster surrounded by a calyx- 

 like involucre of united bracts; stamens 9 1. ERIOGONUM. 



Leaves with sheathing stipules; flowers not in clusters surrounded by involucres; 

 stamens 4 to 8. 



Sepals 5; stigmas not brushlike 2. POLYGONUM. 



Sepals 4 or 6; stigmas brushlike. 



Sepals 6; fruit 3-angled; leaves not kidney-shaped 3. RUMEX. 



Sepals 4; fruit flattened ; leaves mostly kidney-shaped 4. OXYRIA. 



1. ERIOGONUM Michx. 



Perennials; leaves entire, basal, the stem 'sometimes bearing a whorl of leaves 

 below the flowers; flowers small, surrounded by an involucre of united bracts, the 

 involucres in heads or umbels. 



Sepals hairy, at least at the base. 

 Flowers bright yellow; stems 10 to 30 cm. high; sepals hairy almost all over. 



1. E. piperi. 

 Flowers yellowish white; stems 2 to 10 cm. high; sepals hairy only at the base. 



2. E. androsaceum. 

 Sepals not hairy. 



Involucres in umbels; leaves green on the upper side 3. E. subalpinum. 



Involucres in one head; leaves densely and closely white-woolly on both sides. 



4. E. depressnm. 



