970 CARDUACEAE 



36. A. falcata Rydb. Tall perennial, with a rootstock; stem 6-10 dm. high, 

 loosely floccose; leaves linear or narrowly linear-lanceolate, 10-15 cm. long, 

 green and glabrate above, white-tomentose beneath, the upper simple, falcate, 

 the lower usually with several alternate, spreading and strongly falcate, narrow 

 lobes; panicle very large; involucre about 4 mm. high and fully as broad, densely 

 floccose; outer bracts ovate, acute, the inner oval and obtuse; ray-flowers 5-7. 

 Banks: S.D. — Sask. Plain. Au-S. 



37. A. potens A. Nels. Perennial, with a creeping rootstock; stem simple, 

 pale green, 4-8 dm. high; leaves 3-6 cm. long, sessile, pale and glabrate above, 

 thinly tomentose beneath, with somewhat revolute margins, linear, simple or 

 pinnatifid, with 2-4 divaricate lobes; heads numerous in a dense narrow panicle, 

 crowded; involucre 3 mm. high and as broad; bracts 8-10, nearly glabrous, the 

 outer ovate, acute; inner bracts oval, obtuse; ray-flowers 10-12. Banks: Calif. 

 —Mont.— B.C. 



38. A. Underwoodii Rydb. Perennial, with a horizontal much-branched 

 rootstock; stem slender, 2-6 dm. high, somewhat floccose; leaves 3-5 cm. long, 

 pinnately parted, with 3-7 (usually 5) linear or linear-lanceolate acute lobes, 

 densely white-floccose beneath, green and slightly tomentose above, in age gla- 

 brate; panicle narrow; heads crowded; involucre 3 mm. high and 2.5 mm. broad; 

 bracts ovate, tomentose, slightly scarious on the margin. Hills and mountain 

 sides: Nev. — Colo. — Ariz. — Calif. — B.C. Plam — Submont. Jl-S. 



39. A. Lindleyana Besser. Perennial, with a cespitose rootstock; stem 1-^ 

 dm. high, slender; leaves lanceolate to linear, 1-3 cm. long, entire or the lower 

 with sharp teeth, floccose when young, soon glabrate above, more or less per- 

 manently tomentose beneath; inflorescence narrow, racemiform, or with short 

 erect branches; involucres 3-4 mm. high, 2-3 mm. broad, tomentose. Rocky 

 banks: Wash. — w Mont. — Ariz. — n Calif. Son. — Submont. Jl-S. 



40. A. gnaphaloides Nutt. Perennial, with a slender, horizontal, cespitose 

 rootstock; stem 3-6 dm. high, white-tomentose; lower leaves oblanceolate, entire 

 or serrate, 2-10 cm. long, tomentose on both sides; upper leaves lanceolate or 

 linear, entire; heads very numerous, in rather dense panicles; involucres about 4 

 mm. high, 2-3 mm. wide, about 20-flowered. Prairies and river banks: Ont. — 

 Mo. — Tex. — Colo. — Alta.; adv. eastward to N.H. and N.Y. Plain — Submont. 



41. A. pabularis (A. Nels.) Rydb. Perennial, with a creeping rootstock; 

 stem 2-4 dm. high, slender, white-tomentose; leaves linear or narrowly linear- 

 lanceolate, the lower often toothed, densely tomentose, inclined to become 

 yellowish, 3-5 cm. long; heads small, in a narrow spike-like inflorescence; invo- 

 lucres tomentose, about 3 mm. high and 2 mm. broad, about 15-flowered. A. 

 rhizomatapahidaris A. Neh. Saline soil: S.D. — Neb. — Colo. — Ida. Plain. Jl-Au. 



42. A. Purshiana Besser. Perennial, with a horizontal rootstock; stem 3-6 

 dm. high, tomentose; leaves ovate to lanceolate, entire or the lower somewhat 

 toothed, white-tomentose on both sides; heads small, in a dense, contracted pan- 

 icle; involucres about 3 mm. high, 2 mm. broad, tomentose; flowers about 15. 

 Plains: Sask. — Neb. — Calif. — B.C. Plain — Subinont. Au-0. 



43. A. pudica Rydb. Perennial, with a horizontal rootstock; stem 4-6 dm. 

 high, simple up to the inflorescence, white-floccose; leaves linear or narrowly 

 linear-lanceolate, 6-10 cm. long, 6-8 mm. wide, entire, white-floccose on both 

 sides; inflorescence a narrow panicle; involucres campanulate, about 5 mm. high 

 and 4 mm. broad; bracts ovate, densely tomentose, with a darker midrib and 

 slightly scarious margin; flowers about 20, yellow. Mountains: Colo. Submo7it. 

 Jl-Au. 



44. A. argophylla Rydb. Perennial, with a strong rootstock; stem 5-10 

 dm. liigh, white-tomentose, angled; leaves many, lanceolate, entire, or the lower 

 oblanceolate, sometimes coarsely toothed or with lanceolate lobes, 5-10 cm. long, 

 white-tomentose on both sides, acute; heads numerous in a leafy panicle; invo- 

 lucre hemispheric, 4-5 mm. high, 5-7 mm. broad, densely tomentose; bracts 12- 

 14, the outer lanceolate, acute; inner bracts elliptic or oval, obtusish; flowers 

 25-40; corollas yellow. Valleys: Colo, — Wyo. — Wash. — n Calif. 



