966 CARDUACEAE 



4. A. caudata Michx. Biennial; stem glabrous, 5-20 dm. high; leaves 1-3- 



yellow. Sandy soil: N.B.Fla. Tex. Colo. Sask. Jl-S. 



5 A Forwoodii S. Wats. Biennial; stem 4-7 dm. high, somewhat pubes- 

 cent 'when young; basal leaves 5-10 cm. long, petioled, bi- or tripinnatifid into 

 narrowly linear divisions, loosely silky-canescent at least when young; heads 

 numerous in a dense panicle, mostly erect, heterogamous; involucre subglobose, 

 2-2.5 mm. high, 2.5-3 mm. broad; bracts in 3-4 series, the outermost lanceolate 

 or ovate, acute, half as long as the innermost ones; ray-flowers 15-20. A. cau- 

 data calvens Lunell. Plains: Ont. Mich. Neb. Sask. Plain. 



6. A. pacifica Nutt. Perennial; stem 4-10 dm. high, glabrate or sparingly 

 pubescent when young, often purplish; leaves 1-2 cm. long, twice pinnatifid, 

 with narrowly linear divisions; heads very numerous, in a leafy panicle, at first 

 nodding, soon erect; involucre subglobose, about 2.5 mm. high, 2.5-3 mm. broad; 

 bracts glabrous or sparingly short-hairy, scarious-margined ; outermost bracts 

 ovate, acute, about half as long as the inner ones; ray-flowers 8-12; corollas gla- 

 brous. A. desertorum Scouleriana Besser. A. Scouleriana Rydb. Plains: Alta. 

 B.C. Ore.; (? Colo.). 



7. A. camporum Rydb. Perennial; stem 3-5 dm. high, striate, often 

 purplish; basal leaves clustered, 4-10 cm. long, petioled, twice or thrice pinnatifid 

 into linear or oblong divisions, more or less silky-canescent; upper stem-leaves 

 sessile, pinnatifid, with narrowly linear divisions; heads numerous in a narrow 

 leafy panicle, nodding; involucre hemispheric, 2.5-3 mm. high and fully as broad; 

 bracts in 3-4 series, scarious-margined, the outermost ovate, obtuse, a little 

 more than half as long as the innermost ones; ray-flowers 15-20. A. canadensis 

 Nutt., not Michx. A. Forwoodii Rydb. (Fl. Colo.), not S. Wats. Plains and 

 hills: Ont. Sask. Neb. Ariz. Yukon. Plain Submont. 



8. A. MacCallae Rydb. Perennial; stem 2-3 dm. high, rather strict, more 

 or less canescent, sometimes purplish; basal leaves 5-10 cm. long, petioled; blades 

 ovate in outline, twice pinnatifid, with rather few, linear or narrowly oblanceolate 

 divisions, silky-canescent; upper stem-leaves less divided; heads rather numerous, 

 in narrow panicles; involucre 3 mm. high, 4-5 mm. broad; bracts green with 

 yellowish scarious margins, acutish, sparingly long-hairy or glabrous; outer bracts 

 ovate, about half as long as the inner broadly oval ones; ray-flowers 10-15. 

 Gravelly slopes: Alta. Yukon Wash. Colo. Plain Submont. 



9. A. Bourgeauana Rydb. Perennial; stem 3-4 dm. high, rather densely 

 silky-villous, more or less tinged with red; basal leaves clustered, 4-6 dm. long, 

 petioled, sericeous-canescent on both sides, twice pinnatifid, with oblanceolate 

 divisions; stem-leaves mostly sessile, rather small, with linear divisions, or 3-fid 

 or entire; heads very numerous, in dense leafy panicles; involucre hemispheric, 

 about 4 mm. high and 5 mm. broad; bracts yellowish, silky-villous, scarious- 

 margined, the outermost about half as long as the innermost, ovate, acute; ray- 

 flowers about 20. Plains: Sask. N.D. Plain. 



10. A. spithamaea Pursh. Perennial; stem 1-3 dm. high, sericeous; basal 

 leaves pmnately or bipinnately divided into oblanceolate lobes, silky-canescent 

 on both sides; upper leaves reduced, linear or with linear lobes; heads compara- 

 tively few, in a spiciform inflorescence; involucres 4-5 mm. broad; bracts oval, 

 silky or glabrate, with brownish green centres, and scarious margins; flowers 

 brown or purplish. A. borealis Am. auth. A. groenlandica Wormsk. Sub- 

 arctic, arctic, and alpine regions: Greenl.Que. Mont. Colo. Wash. Sub- 

 alp. Alp. Jl-Au. 



11. A. filifolia Torr. Undershrub, 3-10 dm. high; branches erect, minutely 

 tomentulose, leafy; leaves all slender, entire and filiform, or some 3-parted with 



Worm divisions, minutely tomentulose, more or less fascicled; heads very small 

 and very numerous, in narrow leafy panicles; involucres 1-1.5 mm. broad, to- 



