THISTLE FAMILY 1013 



50. C. pulcherrimum (Rydb.) K. Schum. Stem about 4 dm. high, very 

 leafy, grayish tomentose; lower leaves 1-L5 dm. long, pinnately divided, bright 

 green and glabrate above, densely white-tomentose beneath; segments lanceolate 

 or triangular, lobed and toothed with slender spines 3-5 mm. long, the upper 

 sessile and half-clasping; heads 2.5-3 cm. high, 2.5-4 cm. broad; outer bracts 

 lanceolate, slightly floccose, tipped with yellow spines about 5-7 mm. long; flow- 

 ers rose-colored. Carduus pidcherrimus Rydh. Plains: Wyo. — Colo. Siibmonl. 

 Jl-Au. 



51. C. oblanceolatum (Rydb.) K. Schum. Stem rather slender, 3-6 dm. 

 high, densely white-tomentose; lower leaves about 1 dm. long, thick, merely 

 spinulose-dentate or rarely with a few triangular lobes, loosely floccose above, 

 densely white-tomentose beneath; spines slender, 2-5 mm. long; upper leaves 

 lanceolate, sessile and half-clasping; heads 1-3, campanulate, 3-3.5 cm. high, 

 1.5-2.5 cm. broad; bracts slightly floccose at first, with slender divergent spines 

 3-5 mm. long, the innermost unarmed; •flowers rose-colored. Carduus oblanceo- 

 laius Rydb. Mountains: Colo.— Wyo.— Utah— Mont. Jl-S. 



52. C. Flodmanii (Rydb.) Arthur. Stem comparatively slender, 5-10 dm. 

 high, white-floccose; leaves deeply pinnatifid (or those of the seedlings entire), 

 with narrowly lanceolate lobes, tipped with short prickles, densely tomentose 

 beneath, floccose above; heads 3-4 cm. high and nearly as broad; bracts more or 

 less floccose vvhen young, the outer ovate and with short ascending or spreading 

 spines; the innermost hnear-lanceolate, attenuate into a weak tip; corollas rose 

 or rose-purple. Carduus canesccns Pammel, mainly, not Cirsium canescens Nutt. 

 Carduus Flodmanii Rydb. Carduus fdipendulus A. Nels., not Rydb. Meadows 

 and river valleys: Sask. — Minn. — la. — ^Colo. — Mont. Plain — Submont. 



53. C. floccosum Rydb. Stem angled, loosely floccose; leaves about 2 dm. 

 long, loosely floccose on both sides, divided two-thirds to the midrib ; lobes 2- 

 cleft, each division lanceolate, 1.5-2 cm. long, tipjjed with spines about 5 mm. 

 long; heads about 3 cm. high, 1.5-2.5 cm. wide; bracts slightly floccose on the 

 margins, the outer lanceolate, with short and weak spines, the innermost attenu- 

 ate into a purplish tip; corolla red-purple. Mountains: Colo. Submont. Jl. 



54. C. undulatum (Nutt.) Spreng. Stem 3-6 dm. high, white-tomentose; 

 leaves pinnately lobed or parted, with ovate or triangular lobes and moderately 

 strong prickles, white-tomentose beneath, floccose or rarely in age glabrous 

 above; heads solitary or few, scattered, 3-4 cm. high and about as broad; bracts 

 numerous, except the innermost ovate to ovate-lanceolate, with short divergent 

 spines, the innermost lance-linear, attenuate into a weak point; corollas rose or 

 rose-pur})le, rarely white. Carduus undulalus Nutt. Dry plains: Mich. — Tex. — 

 Ariz.— B.C. Plnin—Submont. Jl-S. 



55. C. Engelmannii Rydb. Perennial; stem 5-10 dm. high, loosely floc- 

 cose; leaves lanceolate, more or less pinnatifid or the upper entire, with triangular 

 lobes, white-tomentose beneath, loosely floccose above, in age glabrate and dark 

 green, with short spines; heads long-peduncled, 3.5-4 cm. high, 4-5 cm. wide; 

 bracts numerous, slightly tomentose on the margins, ovate, with conspicuous 

 glutinous ridges and short slender, spreading spines, the innermost attenuate; 

 corollas rose-purple. Cirsium virginianum jUipendulum Engelm., not Cirsiutu 

 filipendulum Lange. Carduus fdipendulus Rydb. Plains and waste places: 

 Colo. — Tex.; apparently also Ida. and Mont. Jl-Au. 



C. Engelmannii X ochrocentrum. With the large heads and long .spines of C. ochro- 

 centrum, but the broad non-deciirrent leaves, dark and glabrate above, of C. Engelmannii. 

 Colo. 



C. Engelmannii X megacephalum. Resembling C. Engelmannii, but the heads larger 

 and with broader bracts, and the leaves broader and conspicuously auriculate-clasptng. 

 Colo. 



56. C. megacephalum (A. Gray) Cockerell. Stem 3-7 dm. high, tomen- 

 tose; leaves broadly oblanceolate or lanceolate, pinnatifid, with short triangular 

 lobes, moderately stout-spined, densely tomentose beneath, floccose but in age 

 becoming green above; heads peduncled, solitary or few, .5-7 cm. high and as 

 broad; bracts numerous, all except the innermost with short and slender diver- 



