Rydberg: Studies on the Rocky Mountain flora 305 



longer pedicels (in C. reticulata I cm. long or less) and in its 

 serrate, short-acuminate leaves, which are less pubescent, more 

 shiny, and much less rough above. It grows in gulches and 

 mountain valleys of Colorado. 



Colorado: Golden, Aug. 29, 1895, P. A. Rydberg (herb. N. Y. 

 Bot. Garden) ; Aug. 30, 1895, C. L. Shear 3263; gulch west of Pen- 

 nock's mountain ranch, May 26, 1897, C. S. Crandall 2254. 



Celtis occidentalis L. is included in the Rocky Mountain flora 

 by Coulter & Nelson,* but erroneously so, the writer thinks. 

 Celtis Douglasii Planchon, C. rugosa, and perhaps also C. reticulata 

 Torr. have been mistaken for it. 



URTICACEAE 

 Urtica strigosissima sp. nov. 



Perennial, dioecious; stem I m. high or more, glabrous below, 

 strongly retrorsely strigulose above, but almost without bristles; 

 stipules narrowly linear-lanceolate, acuminate; petioles 2-3 cm. 

 long; leaf blades lanceolate, 3-5-ribbed, sharply serrate, rounded 

 or acute at the base, long-acuminate at the apex, 5-10 cm. long, 

 1.5-5 cm. wide, finely strigulose beneath; flower clusters slender, 

 the upper almost equalling the leaves; sepals ovate, about equal- 

 ling the achenes. 



This species resembles U. gracilis Ait. in habit and leaf form, 

 but is more strigose and rarely at all bristly. In pubescence it 

 resembles U. Breweri S. Wats, but has narrower leaves and nar- 

 rowly linear-lanceolate, acuminate, instead of oblong and obtuse, 

 stipules. It grows on river banks at an altitude of 1,000-2,500 m. 



Idaho: Forest, Nez Perces County, July 29, 1896, A. A. & 

 E. Gertrude Heller 3475 (herb. Columbia University). 



Urtica viridis sp. nov. 



Perennial with a horizontal rootstock, dioecious; stem 1-1.5 

 m. high, slender, glabrous or sparingly bristly, round-angled; 

 stipules linear-lanceolate, acuminate, 5-8 mm. long; petioles short, 

 one fifth to one third as long as the leaf blades; these from narrowly 

 lanceolate to ovate, coarsely toothed, 4-10 cm. long, thin, light 

 green, almost glabrous; panicles many-flowered, often equalling 

 the upper leaves: sepals oval or ovate, usually half longer than 

 the achenes. 



* New Man. Bot. Cent. Rocky Mts. 143. 



