THISTLE FAMILY 917 



4. A. monocephala DC. Stem 5-10 cm. high; leaves of the rosettes cus- 

 pidate-mucronate, 8-15 mm. long, silky-tomentose beneath; stem-leaves linear, 

 5-10 mm. long; involucres about 5 mm. high and 8 mm. broad; bracts of the 

 (rare) staminate heads broadly ovate, obtuse or acutish, those of the pistillate 

 heads lanceolate, the outer obtuse, the inner acute or acuminate. Arctic-alpine 

 situations: Alaska B.C. Alta. Alp. Jl. 



6. A. chlorantha Greene. Stem 7-15 cm. high; basal leaves and those of 

 the rosettes mucronate or acutish, loosely floccose, densely and permanently so 

 beneath, 1.5-2.5 cm. long; stem-leaves oblong-linear; heads 3-6, somewhat con- 

 glomerate; involucres about 7 mm. high; bracts of the pistillate heads with dark 

 olive-green tips, the outer obtuse, the inner acute or acuminate. Mountains- 

 B.C. Mont. Jl-Au. 



6. A. pulvinata Greene. Stem 5-10 cm. high, densely white-tomentose; 

 leaves of the rosettes densely white-tomentose on both sides, with loose villous 

 tomentum; stem-leaves oblanceolate or oblong, acute; heads 5-8, in a dense 

 cluster; bracts of the staminate heads brown, oblong and obtuse, those of the 

 pistillate heads similar, but the inner more lanceolate and acute. Mountains: 

 Alta. Mont. B.C. Mont. Alp. Je-Au. 



7. A. albescens (E. Nels.) Rydb. Stem 1 dm. or less high, tomentose; 

 leaves of the stolons 4-8 mm. long, densely and closely white-tomentose, obovate; 

 stem-leaves oblanceolate; heads 3-5 in a dense subcapitate cluster; bracts ellip- 

 tic, obtuse, light brown or yellowish. A. pulvinata albescens E. Nels. Moun- 

 tains: Alta. Mont. Ida. Submont. Subalp. Je-Jl. 



8. A. fusca E. Nels. Stem 1-1.5 dm. high, tomentose; leaves of the 

 rosettes 15-22 mm. long, white-tomentose, with a close silky pubescence; stem- 

 leaves linear or linear-oblanceolate ; heads 3-13, pedicellate, corymbose; bracts 

 of the pistillate heads elliptic or oblong, obtuse, greenish brown. Open woods: 

 Wyo. Ida. Mont. Au. 



9. A. acuta Rydb. Stem slender, 5-12 cm. high; leaves of the rosettes 

 15-25 mm. long, 2-4 mm. wide; stem-leaves narrowly linear or linear-oblanceo- 

 late; heads 3-5, conglomerate, sessile; bracts of the pistillate heads lanceolate to 

 linear-lanceolate, dark greenish brown with slightly lighter tips, the inner acute. 

 Mountains: Alta. Subalp. Alp. Jl-Au. 



10. A. media Greene. Stem 5-10 cm. high, loosely tomentose; leaves of 

 the rosettes 1-2 cm. long; heads 4-7, densely conglomerate; bracts of the stam- 

 inate head elliptic and obtuse, very dark green, or the innermost sometimes with 

 whitish tips; outer bracts of the pistillate head oblong, obtuse, the inner lanceo- 

 late, acute. A. austromontana E. Nels. Higher peaks: Alta. Colo. Calif. 

 B.C. Alp. Subalp. Jl-Au. 



11. A. mucronata E. Nels. Stem 5-12 cm. high, tomentose; leaves of the 

 rosettes oblanceolate or narrowly spatulate, 1-2 cm. long; stem-leaves oblong- 

 linear, acute; heads 4-8, conglomerate; bracts in both the pistillate and the 

 staminate heads oblong or elliptic, obtuse, dark brownish green, the inner bracts, 

 especially in the staminate heads, often with whitish tips. Mountains and rocky 

 slopes: Alta. Wyo. B.C. Alp. Subalp. 



12. A. Sansoni Greene. Stem 1-2.5 dnj. high, slender; leaves of the rosettes 

 linear-spat ulate or oblanceolate, 1-2 cm. long; stem-leaves linear, acute or acum- 

 inate, erect; heads 8-10, cymose and peduncled; involucres 6-7 mm. high and 

 nearly as wide ; bracts of the pistillate heads oblong or lanceolate, the inner acute, 

 brownish below, dirty white, yellowish or pinkish towards the apex, those of 

 the staminate heads oblong, obtuse. Hills and mountains: Alta. Mont. B.C. 

 Submont. Je-Jl. 



13. A. flavescens Rydb. Stem about 1 dm. high; leaves of the stolons 

 broadly spatulate, about 1 cm. long, acute, densely tomentose on both sides; 

 stem-leaves oblong or linear; heads 4-8, in a dense subcapitate cluster; involucres 

 4-5 mm. high, 5 mm. broad; bracts isabel-colored or yellowish, in the staminate 

 heads broadly elliptic, in the pistillate heads oblong, in both obtuse. A. reflexa 

 E. Nels., in part. Dry hills: Mont. Colo. Wash. Submont. Mont. My-Jl. 



