COMPOSITAE (COMPOSITE FAMILY) 569 



tomentose, usually much branched, 3-12 dm. high: leaves lanceolate or oblong, 

 3-7 cm. long, 4-12 mm. wide, entire or the lower somewhat toothed, white- 

 tomentose on both sides, acute or acuminate, sessile or the lower narrowed 

 into short petioles: heads numerous, erect, spicate-paniculate, above 3 mm. 

 broad; involucre oblong, tomentose. (A. rhizomata A. Nels. Bull. Torr. Bot. 

 Club 27: 34. 1900; A. pudica Rydb. 1. c. 32: 130; A. pabularis Rydb. 1. c. 33: 

 157; probably A. candicans and A, floccosa Rydb. 1. c. 24: 296; A. Purshiana 

 Bess.) From the Missouri river to the Pacific. This as well as A. ludoviciana 

 includes a multitude of forms impossible of discrimination. Some of the more 

 important ones that have received specific names are indicated and a few are 

 given varietal rank. Leaf outline and incision are wholly valueless as diag- 

 nostic characters, since all possible gradations occur in both groups. 



15a. Artemisia gnaphalodes diversifolia A. Nels. Many or most of the 

 leaves deeply pinnately cleft into narrow lobes. (A. diversifolia Rydb. 1. c. 

 28: 20. 1901.) Colorado to Montana. 



16. Artemisia ludoviciana Nutt. 1. c. Perennial, ascending or erect, lower 

 than the preceding, 3-5 dm. high, branched; stem somewhat tomentose: leaves 

 oblanceolate or somewhat cuneate in outline, 2-5 cm. long, densely white- 

 tomentose beneath, floccose but greener above, deeply 3-7-lobed with lanceo- 

 late lobes, or the upper entire: heads very small and numerous, somewhat 

 nodding; involucre oblong-campanulate, tomentose, but less so than in the 

 preceding. (A. Underwoodii and A. Brittonii Rydb. 1. c. 32: 129; A. latiloba 

 Rydb. Mem. N. Y. Bot. Card. 1: 429. 1900.) In the western half of North 

 America. 



17. Artemisia mexicana Willd. Spreng. Syst. 3: 490. 1825. Paniculately 

 branched, 4-10 dm. high, less tomentose: leaves narrow-lanceolate to linear, 

 commonly attenuate, some 3-5-cleft or parted; radical cuneate, incisely 

 pinnatifid or trifid: heads very numerous in an ample loose panicle, many- 

 pedicellate, 3-4 mm. long; involucre arachnoid-canescent or glabrate, largely 

 scarious. From Nevada through the southern part of our range to Texas. 



17a. Artemisia mexicana silvicola (Osterh.) A. Nels. "Distinguished by 

 its fewer and larger leaves, the more lax inflorescence, and larger heads." 

 These differences probably due to the moisture and shade of its habitat. 

 (A, silvicola Osterh. 1. c. 28: 645.) Northern Colorado, on shaded stream 

 banks. 



176. Artemisia mexicana Bakeri (Greene) A. Nels. A slender form with 

 short, linear, entire leaves on the branchlets and the lower with remote pinnate 

 segments: the whole plant greenish but lightly arachnoid-canescent. (A. 

 Bakeri Greene, PI. Baker. 3: 31. 1901.) Canon of the Gunnison, Colorado. 



18. Artemisia paucicephala A. Nels. 1. c. 35. Tufted on woody rhizomes, 

 thinly but permanently silvery-tomentose throughout; stems numerous, leafy 

 to the summit, erect, simple or sparingly branched, 2-4 dm. high: leaves 4-8 

 cm. long, entire or deeply pinnatifid, linear to lanceolate, some with a broad, 

 3-5-cleft apex, nearly all with a narrowed, petiole-like base: heads few, 

 racemosely disposed on the main stem and its slender branches (if any), rather 

 large, sessile or short-pediceled, broadly campanulate, about 5 mm. in diam- 

 eter (40-60-flowered) ; involucral bracts oval or ovate, scarious-margined : the 

 pistillate flowers few, very slender, with linear-clavate styles. (A. gracilenta 

 A. Nels. 1. c.) Sandy banks near Yellowstone Lake. 



19. Artemisia franserioides Greene, Bull. Torr. Bot. Club 10: 42. 1883. 

 Glabrous except on the lower face of the leaves, or minutely and obscurely 

 puberulent; stem rather stout, 4-8 dm. high: leaves comparatively ample, 

 green above, pale and cinereous beneath; the lower bipinnately and the upper 

 simply pinnately parted into lanceolate-oblong obtuse, entire or 2-3-cleft 

 divisions and lobes: heads numerous, loosely racemose on the branches of the 

 leafy elongated panicle, 4-6 mm. broad. Mountains of Colorado, New Mex- 

 ico, and Arizona. 



20. Artemisia discolor Dougl. in Herb. Hook.; DC. Prodr. 6: 109. 1837. 

 Stems mostly slender, 2-3 dm. high, from a slender lignescent caudex: leaves 

 1-2-pinnately parted into narrow linear or lanceolate-entire or sparingly 



