THISTLE FAMILY 967 



mentulose, 3-5-flowered; sterile central flowers 1-3. A. platlensis Nutt. Plains: 

 Neb. — Tex. — Ariz. — Nev.; Alex. Son.— Plain. Ap-0. 



12. A, pedatifida Nutt. Perennial, with a thick woody cespitose caiidex; 

 stems 5-15 cm. high, finely canescent; leaves mostly basal, once or twice ternatcly 

 divided into linear or narrowly spatulate divisions, finely white-tomentulose; 

 heads few in a spicate or racemose inflorescence, 12-15-flowered; involucres 3-4 

 mm. broad, tomentose; bracts elliptic; flowers brownish. Arid ground; Wyo. — 

 Mont. — Ida. Snbmont, Je-Au. 



13. A, Absinthium L. Shrubby; stem 5-15 dm. high, finely canescent; 

 leaves 5-12 cm. long, once to thrice pinnately divided into oblong or lanceolate, 

 obtuse divisions, finely canescent, especially beneath; heads numerous in a large 

 panicle, with racemiform branches, nodding; involucres 4-5 mm. broad, canes- 

 cent; outer bracts linear, the inner oval, scarious-margined. Waste places and 

 around dwellings: Newf.— N.C.— Mont.; escaped, native of Eu. Au-S. 



14. A. frigida Willd. Perennial, with a cespitose, suffrutescent caudex; 

 stem 2-5 dm. high, finely canescent; leaves twice pinnatifid, with linear-filiform 

 divisions, silvery-white, in age often turning brownish; heads numerous, race- 

 mosely disposed, nodding; involucres 4-6 mm. broad, canescent or tomentose; 

 bracts oblong or lanceolate; corollas yellow, glabrous. Dry plains and hills: 

 Hudson Bay— Tex. — Ariz.— Ida.— Alaska; Asia. Plain— MonL Jl-0. 



16, A. scopulorum A. Gray. Perennial, with a cespitose caudex; stem 

 simple, canescent, 1-2 dm. high; lower leaves petioled, 3-7 cm. long, bipinnatifid, 

 with linear or oblong divisions, silky-canescent; upper stem-leaves small and 

 less divided; heads 3-12, spicately or racemosely disposed, 18-30-flowered; invo- 

 lucres 6-8 mm. broad; bracts oval, tomentose, black- or bro^\'n-margined; corollas 

 yellow, hirsute at the summit. High mountains: Mont. — N.M,— Utah, Sub- 

 alp. — Alp. Jl-S. 



16 A Pattersoni A. Gray. Perennial, with a cespitose caudex; stem white- 

 tomentose' lower leaves pinnatifid, with 3-5 linear divisions, sericeous; upper 

 stem-leaves linear, entire or 2-3-cleft at the apex; heads 1-5, usually conglomer- 

 ate 8-12 mm. broad; bracts oblong or elliptic, white-tomentose with browri or 

 black margins; flowers yellow, 40-50, the central ones fertile; receptacle \aUous. 

 Alpine peaks: Colo. Subalp,~-Alp. Jl-Au. 



xi'iU^ "Ripnnial! fitftm 3-10 dm. hish. dabrc 



biennis 



divisions, gla- 



brous" heads small, numerous, in a dense leafy panicle; involucres z-6 mm. wiae, 

 elabrous- bracts elliptic, dark-green, scarious-margined; corollas yellow, glabrous. 

 Wet places: N.S.— N.J.-Calif.— B.C.-Mack. Pkiin—MonL Au-D. 



18 A minuta Rydb, A low undershrub, woody at the base; stems 1 dm. 

 high or less, at first sHghtly tomentose, in age glabrate and reddish; leaves mostly 

 basal, silvery-silky, about 1 cm. long, pinnatifid with 5-7 narrowly oblanceolate 

 approximate divisions; stem-leaves smaller, with hnear-filiform divisions; in- 

 florescence simple, spike-like, 2-4 cm. long; involucre hemispheric, 2.5 mm. high, 

 bracts about 10, light brown, slightly tomentose, m age glabrate, ovate, acutish, 

 scarious-margined. Plains: Alta. Plain. 



19 A Tvrrellii Rydb. Tufted perennial; stems 2-3 dm. high, densely 

 silky-canescent; leaves 1.5-3 cm. long, white-silvery on both sides, the basal ones 

 twice pinnatifid, with 3-5 crowded primary divisions, which are 3-5-cleft mto 



SS'Sos , S^^^ rn;oluc7e hTm^^^^^^ about 5 mm. high and 7 mm. 

 KrS-Ss 12-15 elliptic, densely canescent on the back, with conspicuous 

 darf 'browf sJLiou^ my-flowers about 10; disk-flowers about 30. 



Mountains: B.C. Subalp. S. ^ 



saxicola 



dm 



decumbent 



twice pinnately parted into lanceolate divisions loosely villous, Heads several, 

 twice Pi™'^^?'^ J* . of them, at least the lower, on long erect peduncles, 



racemosely disposed, some oi T'"^"^'/^ .,, ^,^. ,.^ Juntin with hlack or dark 



8-10 mm 



