132 GENUS ARTEMISIA. 



like the lower; inflorescence raceme-like or spike-like, sparsely leafy, 1 to 7 cm. long by 

 about 0.5 cm. broad; heads heterogamous, short-peduncled or subsessile, erect; involucre 

 hemispheric, about 3.5 mm. high, 3 to 4 mm. broad; bracts 6 to 10, round-oval, obtuse 

 or slightly acute, moderately unequal, scarious-margined, the outer ones densely tomentu- 

 lose; receptacle naked; ray-flowers 4 to 7, fertile, corolla 1.5 to 2 mm. long, very slender, 

 constricted at the few-toothed summit; disk-flowers 5 to 10, sterile, corolla tubular- 

 funnelform, 3 to 3.5 mm. long, 5-toothed, rose-colored toward the summit, glabrous; 

 style of disk-flowers 2.5 to nearly 3 mm. long, 2-cleft at summit, the branches 

 penicillate at apex or the branches sometimes fused along one sinus, the other remaining 

 open, probably completely fused in some cases; ach^nes ellipsoid, faintly ribbed, glabrous, 

 those of the disk-flowers wanting. 



Northern Rocky Mountains on dry plateaus and ridges. Wyoming, Idaho, and 

 probably Montana. Type locality, arid plains of Lewis (Snake) River. Collections: 

 Steamboat Mountain, Sweetwater County, Wyoming, Nelson 7058 (Gr, NY, UC); 

 Cooper Lake, Albany County, Wyoming, Goodding 21 (Gr, NY, UC, US); type col- 

 lection, Nuttall (Gr, Phila.). 



RELATIONSHIPS. 



The shrubby habit, reduced number of flowers, narrow disk-corollas, and the cleft 

 styles of the disk-flowers all indicate A. pedatifida as an ally of A. fiUfolia, notwithstand- 

 ings its very different appearance. It is the high-altitude and northerly representative 

 of that, with the woody portion and the inflorescence much reduced. Whether either of 

 these species has been derived from the other can not be stated definitely, for intermediate 

 forms do not now exist. Notwithstanding the plainly sterile disk-flowers A. pedatifida 

 was originally placed in the section Abrotanum, presumably through an oversight. It is 

 in no way connected with any of the forms of that group. A notable peculiarity of the 

 species is the remarkable length of the disk-corollas, these averaging about twice as long 

 as those of other and much larger plants of the same section. Because of its low stature, 

 the plant is sometimes confused with A . Iridentala trifida, but — aside from technical char- 

 acters such as the sterile disk-achenes and much larger and broader corollas — pedatifida 

 may be distinguished by the divergent leaf-lobes, the larger heads, the lower of which are 

 distinctly peduncled, and by the gray fibrous bark of the caudex and root. 



ECOLOGY AND USES. 



Artemisia pedatifida is a dwarf shrubby rosette-former, resembling A. spinescens and 

 pygmaea in habit. It forms the characteristic consocies of flat alkaline depressions in 

 Wyoming, and persists for a long time in the succeeding Agropyrum consociation of the 

 mixed prairie. It is an indicator of the presence of alkali in moderate amounts. In the 

 less alkaline associations it is frequently mixed with A. frigida, and less so with A. 

 tridentata. 



The foliage of this Artemisia is doubtless browsed to a limited extent by cattle and 

 sheep, but the plants are too small to be compared in value with the larger sagebrushes. 

 Since also the species is of limited distribution, its economic importance is apparently 

 quite negligible. 



24. ARTEMISIA SPINESCENS D. C. Eaton, in Watson, Bot. King's Expl. 180, 1871. 

 Plate 17. Bud Sagebrush. 



A rounded spiny shrub, 0.5 to 5 dm. high, with a strong penetrating odor and bitter 

 taste; stems crowded, much branched from the base, thick and rigid, the older parts 

 with a brown fibrous bark, the twigs ascending, not striate, white-tomentose or short- 



