1006 CARDUACEAE 



Spines of the middle bracts stout and ascending. 



Upper leaves entire or with shallow lobes; involucre less than 2 cm. 



broad, very dark. 49. C. canescens. 



Upper leaves deeply pinnatifid; involucres about 3 cm. broad, light 

 colored, except the viscid ridge. 50. C. pulcherrimum. 



Spines of the middle bracts 5 mm. long or less, weak and spreading. 



Leaves, at least the upper ones, entire or slightly lobed, tomentose on both 

 sides. 51. C. oblanceolatum. 



Leaves pinnately divided or deeply lobed. 



Leaves deeply pinnatifld, with narrow, linear-lanceolate lobes; plant 



yellowish. 52. C. Flodmanii. 



Leaves with triangular or ovate-lanceolate lobes. 



Bracts with very inconspicuous glandular ridge, not at all viscid. 



53. C. floccosum. 

 Bracts with a conspicuous glandular ridge, surrounded by a viscid 



area. 



Leaves tomentose on both sides. 54. C. undulatum. 



Leaves glabrate and dark green above. 55. C. Engclmannii. 

 Involucres 4-7 cm. in diameter. 



Spines of the involucral bracts rarely more than 5 mm. long; leaves not con- 

 spicuously decurrent. 56. C. megacephalum. 

 Spines of the middle bracts fully 1 cm. long; leaves narrower, conspicuously 



decurrent. 57. C. ochocenlrum. 



Leaves greenish and sparingly floccqse on both sides; bracts linear-lanceolate, very viscid, 

 with stout erect or ascending spines. 41. C. canovirens. 



XI. ARVENSIA. 

 One species. 58. C. arvense. 



1. C. Parryi (A. Gray) Petrak. Stem 3-10 dm. high; lower leaves petioled, 

 oblanceolate, 2-4 dm. long, stem-leaves lanceolate or linear in outline, sessile, 

 with auriculate-clasping bases, more or less lobed with triangular teeth and weak 

 spines; heads several, spicately-glomerate, leafy-bracted, 2-3 cm. high; outer 

 bracts with weak spines, the inner mostly with lanceolate-erose tips, spineless. 

 Cnicus Parryi A. Gray. Carduus viridiflorus Greene. Mountains: Colo. 

 Utah N.M. Ariz. Submont. Subalp. 



2. C. araneans Rydb. Stem slender, about 5 dm. high, slightly arach- 

 noid; leaves linear in outline, 10-12 cm. long, slightly arachnoid or glabrate and 

 bright green above, grayish tomentose beneath, pinnatifld, with oblong, moder- 

 ately strongly spine-tipped lobes; heads at the ends of the branches, 2.5-3 cm. 

 high; outer bracts tapering into a stout broad-keeled spine, the inner with narrow 

 lanceolate erose tips. Perhaps of hybrid origin. Carduus araneosus Osterh., 

 not Steud. Banks: Colo. Submont. Mont. Je-Au. 



3. C. scariosum Nutt. Stem slender; leaves densely white-tomentose 

 beneath, pinnatifid with short lobes; heads about 3 cm. high; bracts lanceolate 

 to lance-subulate, the outer spinulose-ciliate, the inner with lanceolate-erose tips. 

 Carduus scariosus Hook. C. Hookerianus Rydb. (Fl. Mont.), in part. Moun- 

 tains: Wyo. Mont. Submont. Jl-Au. 



4. C. subniveum Rydb. Stem 6-10 dm. high, white-floccose, paniculatelv 

 branched above; leaves 1-1.5 cm. long, linear in outline, deeply pinnatifid, 

 tomentose on both sides, densely so and white beneath, more loosely so above; 

 lobes lanceolate or triangular, often toothed or lobed and armed with moderately 

 strong yellow spines; involucres 2 cm. high and nearly as broad, densely arachnoid, 

 almost floccose; outer bracts with ascending spines, 5 mm. long, the inner with 

 subulate weak tips. Valleys: w Wyo. Au. 



5. C. Kelseyi Rydb. Stem 5-20 dm. high, very leafy; leaves linear, at most 

 sinuately short-lobed, green above, somewhat tomentose or glabrate beneath; 

 heads 3-4 cm. high, erect, in a leafy spike-like inflorescence; bracts all linear- 

 lanceolate, attenuate into short spines or slender tips. Carduus Kelseyi Rydb. 

 Mountains: Mont. Plain Submont. Je-Au. 



C. Butleri X Kelseyi. With the inflorescence of C. Kelseyi and the bracts of C. But- 

 leri, but slightly arachnoid-hairy. Mont. 



6. C. Hookerianum Nutt. Stem 3-6 dm. high; leaves scarcely decurrent, 

 pinnatifid, with rather distant, oblong-lanceolate lobes and short spines, densely 

 tomentose beneath, sparingly floccose above; heads 2.5-3 cm. high; bracts linear- 

 subulate, attenuate into short spines. Carduus Hookerianus (Nutt.) Heller . 

 Mountains: Alta. Mont. B.C. Jl-Au. 



