1012 CARDUACEAE 



slender tip, the rest lanceolate with yellow spines 3-5 mm. long; corolla straw- 

 colored. Carduus canovirens Rydb. Meadows and slopes: Mont. — n Wyo. — 

 Ida. Submont. Jl-Au. 



42. C. plattense (Rydb.) Cockerell. Stem 3-7 dm. high, white-tomentose ; 

 leaves deeply pinnatifid into oblong divisions, 3-5 cm. long, tipped with slender 

 short yellow spines, densely white-tomentose beneath, more sparingly floccose 

 above; heads 4-5 cm. high; bracts very numerous, yellow, with dark thick ghitin- 

 ous backs, all exceprt the innermost broad, ovate, lanceolate, with short yellow 

 spreading spines. Carduus plaltcnsis Rydb. Sandy places: Neb.— Colo. 

 Plain . Je- Jl. 



C. plattense X undulatum. Eescmbling C. plattense in the heads and leaf-form, but 

 the former smaller and with narrower and less viscid bracts. Colo. 



43. C. Nelsonii (Pammel) Rydb. Stem 6-10 dm. high, tomentose; leaves 

 deeply pmnatifid, densely white-tomentose beneath, loosely floccose above; 

 lobes with yellow spines; heads scattered, hemispheric, 3-3.5 cm. high, 3-4 cm. 

 wide; bracts very numerous, all except the innermost lanceolate and tipped with 

 short, flattened, yellow, spreading spines. Cnicm Nelsonii Pammel. Plains: 

 Wyo. Plain. 



44. C. palousense Piper. Stem 3-10 dm. high, tomentose; leaves lanceo- 

 olate, pinnatihd, with entire or 2-cleft lobes, graduallv tapering into short spines, 

 white-tomentose beneath, loosely floccose or glabrate above; heads scattered, 

 3-4 cm. high, hemispheric; bracts very numerous, all but the innermost with 

 short slender, terete spines. Carduus paIouse7isis Piper. Meadows: Ore.— Ida. 

 — VVash. Son. Je-Au. 



, , ^P' C'^.Tracyi Rydb. Stem 3-7 dm. high, loosely floccose; leaves oblanceo- 

 late in out hue, divided to near the base, green but slightly floccose above, more or 

 less tomentose beneath ; lobes lanceolate to linear-lanceolate, tipped with yeUow 

 spines o^S mm. long; heads 3-3.5 cm. high and about 3 cm. or less wide; bracts 

 slightlv floccose when 3'oung, yellowish, the outermost and inner narrowlv lanceo- 

 late, the middle ovate-lanceolate, all except the innermost with short spreading 

 spines; innermost bracts attenuate into a linear-lanceolate yellow tip. Carduus 

 Tracyi Rydb. Dry fields': Colo.— Utah. Submont. Je-Jl. 



46. C. nebraskense (Brit ton) LuneU. Stem 3-5 dm. high, tomentose; leaves 

 linear-obiong or lanceolate, white-tomentose beneath, loosely floccose above, 

 entire or irregularly toothed; heads solitary, 3-3.5 cm. high, 3-4 cm. broad; 

 bracts numerous, lanceolate, with short, slender, spreading spines; inner bracts 

 Imcar-lanceolate, tapering into linear-lanceolate spreading tips. Carduus 

 nebraskens7s Britton. Magnesia cUffs: w Neb.— Wyo. Plain. Jl. 



47. C. brevifolium Nutt. Stem tomentose, 3-5 dm. high; leaves oblanceo- 

 late or lanceolate, more or less lobed, with triangular lobes and weak yellow 

 spines, white-tomentose beneath, more loosely floccose above; head solitary, 

 about 3 cm. high and 2.5 cm. broad; bracts fewer than in the related species, ovate, 

 with small erect yeUow spmea, the innermost lance-Unear tapering into a slender 

 yellow tip. Hills and ravines: Sask.— Mont.— Ida. 



48. C. acuatum (Osterhout) Rydb. Stem 8-10 dm. high, striate, floccose; 

 leaves numerous linear m outline, divided halfway to the midrib, the divisions 

 being agam divided into 2 or 3 lanceolate, attenuate, strongly spiny lobes; lower 

 surface densely tomentose, the upper loosely arachnoid, floccose; heads 1&-20 

 mm. ^^-lde; bracts somewhat floccose on the margins, Tvith a narrow glandular 

 dorsa ridge, all except the innermost armed with slender spreading spines, 5-6 

 mm. long. Carduus acuatus Osterhout. River banks: Colo. Submont. Jl. 



nUnt ^rU^^Tf"^ r"""- ^^^""Ai dm high, more or less tomentose; leaves 

 thZ%Z}^^^^ft' ^ Jrr P^f^t^d, with short rounded-oblong lobes, densely 

 ^ hite-tomentose beneath, loosely floccose and at last green above; heads scat- 



h?.ff«f In'^rlT' ^P,^gl«^«^^t^' 2-2-0 cm high, usually less than 2 cm. broad; 

 m<S l;th «tn^+^' ^Mth very broad dark glutinous ridges, aU except the inner- 

 most %vith stout ascending or erect spmes 5-10 mm. lone' corollas rose or rose- 

 purple. Hills and plains: Colo.-Wyo. Plain-Submmt. J^'' 



