THISTLE FAMILY 885 



and slightly clasping, those of the branchlets only 3-5 mm. long; heads numerous, 

 borne at the end of leafj' branchlets; involucre turbinate, 5-8 mm. high, 8-10 

 mm. broad; ligules nimierous, white, 5-7 mm. long. A. hebecladus Coult & Nels., 

 not DC. A. multiflorus A. Gray, in part. Plains: Sask. — N.D. — Colo. — Calif. 

 — Ida. Plain — Suhniont. Jl-0. 



24. A. multiflorus Ait. Stem much branched, 3-6 dm. high; branches 

 mostlj' ascending-spreading; leaves linear, 1-5 cm. long, sparingly hirsute-strigil- 

 lose, or above glabrate; involucre about 4 mm. high and broad; ligules white, 

 3-4 mm. long. Prairies and dry ground : Me. — Ga. — Mex. — Colo. — B.C. Plain. 

 Au-0. 



25. A. stricticaulis (T. & G.) Rydb. Stem 3-6 dm. high, slender; leaves 

 narrowly linear, 1-5 cm. long, 1-2 mm. wide, sparingly strigose or glabrate; 

 involucres 3-4 mm. high and nearly as broad; bracts in 3 series, narrowly oblance- 

 olate, almost glabrous, rather thin; ligules white, 3 mm. long. Meadows and 

 river valleys: Sask. — Neb. — Wash. — Alta. Plain. Au-S. 



26. A. polycephalus Rydb. Stem with many ascending branches, 3-8 dm. 

 high; leaves linear, 2-5 cm. long, hispidulous-strigose or in age glabrate; involucres 

 5-7 mm. high and as broad; ligules white, 4—6 mm. long. Plains and hills: Alta. 

 — Neb. — Tex. — Ariz. Plain — Submont. Jl-S. 



27. A. commutatus T. & G. Stem branched above, with usually spread- 

 ing branches, coarsely strigose; leaves linear, 1-4 cm. long, densely hispid-stri- 

 gose; involucres 6-8 mm. high and fully as wide; ligules white, 4-5 mm. long. 

 A. adsurejens Greene. -'A. incannpilosus Sheld. Plains and river banks: Sask. — 

 Minn. — Kans. — N.]\L — Ariz. — B.C. Plain — Submont. Au. 



28. A. falcatus Lindl. Stem 3-4 dm. high, sparingly strigose; leaves linear, 

 often falcate, 2-4 cm. long; heads more racemosely arranged than in the pre- 

 ceding; involucres 5-6 mm. high and as broad; ligules white or pinkish, 4-5 mm. 

 long. A. Cordineri A. Nels. Valleys: Mack. — Colo. — Alaska. Plain — -Mont. 

 JI-0. 



29. A. denudatus Nutt. Stem 2-4 dm. high, glabrous or nearly so through- 

 out, slender; leaves narrowly linear, 1-5 cm. long, the upper much reduced, 

 rather firm; involucres 5-6 mm. high; outer bracts oblanceolate, rounded at the 

 apex, the inner linear and more acute, all glabrous; ligules 5-8 mm. long. Dry 

 plains: Utah — s Ida. Son. Jl-Au. 



30. A. Wilsonii Rydb. Stem 3-6 dm. high, often purplish, more or less 

 pubescent with long white hairs; lower leaf-blades 5-10 cm. long, usually more or 

 less hirsute on both sides, but in age glabrate, serrate, acuminate, the upper 

 lanceolate, sessile, sub-entire; involucre 7-8 mm. high, scarcely 1 cm. wide; bracts 

 subulate, attenuate, with green oblanceolate midrib; ligules 8-10 mm. long, 

 bluish jiurjile. River valleys: Mack. — B.C. — w Ont. Boreal. Au-S. 



31. A. Lindleyanus T. & G. Stem 3-10 dm. high, with crisp hairy lines 

 above; lower leaf-blades cordate to ovate, serrate, 5-15 cm. long, rather firm; 

 middle leaves with winged ciliate petioles with clasping bases; the uppermost 

 leaves lanceolate, sessile; involucres 7-8 mm. high, about 1 cm. broad; bracts 

 linear-subulate, with a green oblanceolate midrib; disk-flowers reddish purple; 

 ligules bluish purple, 10-12 mm. long. River banks: Lab. — N.H. — Ohio — Wyo. 

 — B.C. — Yukon. Plain — Subalp. 



32. A. MacCallae Rydb. Stems 3-6 dm. high, often purplish, glabrous up 

 to the inflorescence, then -slightly pubescent in lines; lower leaves with winged 

 petioles; blades 8-15 cm. long, usually serrate, acute, glabrous or essentiallj' so; 

 involucres 8-9 mm. high, 1 cm. broad; bracts subulate, glabrous, with linear- 

 lanceolate green tips; ligules blue or bluish purjile, about 15 mm. long; disk- 

 flowers red-])ur])le. Along streams: Alta. — B.C. Mont. Au-S. 



33. A. Butleri Rydb. Stem 4-10 dm. high, slender; lower leaf-blades about 



1 dm. long, distantly serrate; involucres 5-6 mm. high, about 8 mm. wide; bracts 

 subulate, with narrowly lanceolate green tips, attenuate, glabrous; ligules bluish 

 purple, 8-10 mm. long. Along streams: Alta. — Mont. — B.C. Mont. Au-S. 



