THISTLE FAMILY 885 



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

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

 mm. broad; ligules numerous, 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 Submont. Jl-O. 



24. 



mostly 



lose, 



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



Au-O. 



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, 45 mm. long. 

 A. adsurgens Greene. A. incanopilosus Sheld. Plains and river banks: Sask. 

 Minn. Ivans. N.M. 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. 

 Jl-O. 



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 ob lanceolate, 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 purple. 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 essentially so; 

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

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

 flowers red-purple. Along streams: Alta. B.C. Monj. 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. 



