ARTEMISIA COMPOSITE 367 



and close tomentum. Heads homogamous, the flowers all her- 

 maphrodite and fertile Receptacle not hairy. 



* Heads solitary in the axils, surpassed by the rigid leaves. 



A. rigida Gray Proc Am. Acad. xix, 49. " A span to a foot high from a 

 thick woody base or short stem, producing a profusion of rigid and slender 

 rather simple fastigiate branches, leafy to the very top: leaves al.*o rigid, 

 silvery-canescent, filiform-linear, 3-5 parted or cleft, or some of the upper 

 and fascicled ones entire (even the lower rarely inch long), most of them 

 subtending a sessile head: involucre oblong to campanulate, 5-12-flowered, 

 less than 2 lines long ; bracts oval, hyaline-margined. On high rocky ridges, 

 N. E. Oregon and adjacent Idaho. " 



* * More naked-paniculate or thyrsoid, at least the upper heads or 

 clusters exceeding the subtending leaves: heads comparatively small, 

 and few-flowered, mostly oblong, 1-2 lines long; involucral bracts 

 rather firm in texture, well imbricated, the outer successively shorter. 



A. arbuscnla Nutt. I.e. Dwarf. 8-12 inches high, with a stout base 

 and slender flowering branches: leaves short, cuneate or fan-shaped, 

 3-lobed or parted with the lobes obovate to spatulate-linear, sometimes 

 again 2-lobed ; those subtending the heads usually entire and narrow: 

 panicle strict and comparatively simple and naked, often spiciform and re- 

 duced to few rather scattered sessile heads : involucre 5-9-flowered. High 

 mountains and plains, Idaho and Wyoming to Utah and California. 



A. tridentata Nutt. 1. c. A shrub or small tree 2-15 feet high, much 

 branched : leaves cuneate, 6-18 lines long, 3-7-toothed or lobed at the trun- 

 cate summit, uppermost cuneate-linear: heads very numerous, in large 

 dense panicles ; involucre 5-8-flowered, oblong, its outer or accessory bracts 

 short, ovate, obtuse, tomentose-canescent. Common on dry plains and 

 mountains, Brit. Columbia to California and Nebraska, east of the Cascade 

 Mountains. Commonly called Sage Brush. 



Var. angustifolia Gray Proc. Am. Acad. xix, 50. <l Leaves all narrow; 

 lower spatulate-linear, barely 3 toothed at the roundish summit; upper 

 entire and more linear, a line or less wide : heads small : shrub 3 or 4 feet 

 high, with foliage too like that of the following species, but involucre of A. 

 tridentata. A id plains, 8. Idaho and W. New Mexico to the Mohave Des- 

 ert and the southern borders of San Diego Co. California. " 



A. trill da Nutt. 1. c. Silky -canescent : Stems 6-30 inches h : gh, much 

 branched: leaves 3 cleft toward the apex or H-parted, the lobes and en 1 ire 

 upper leaves narrowly linear or slightly spatulate dilated : head-- numerous 

 in ihe Contracted leafy panicle, or spicately disposed on its branches: invo- 

 lucre 3-9-flowered, its outer or accessory bracts oblong to short-linear or 

 lanceolate. Elevated plains, Washington to California. 



Tribe mi, SENECIONIDEJS Gray Syn. Fl. i, pt. 279. Heads 

 heterogamous or homogamous. Involucre mostly one or two series of 

 equal not scarious bracts, sometimes unequal, or even imbricated, 

 with or without short accessory ones at base. Receptacle naked. 

 Anthers without tails at base, but not rarely sagittate. Style-bran- 

 ches of hermaphrodite flowers most commonly truncate or obtuse, 

 tipped with short appendages or none. Pappus of numerous capil- 

 lary bristles, sometimes caducous. 



* Heads suV dioecious : style in the tubular sterile flowers undivided 

 or neaily so. 



