1002 CARDUACEAE 



2. T. canescens DC. A shrub, 3-10 dm. high; branches canescent, leafy; 

 leaves not fascicled, narrowly linear, straight or nearly so, 2-3 cm. long, 1-2 mm. 

 broad, white-tomentose; heads about 15 mm. high; bracts 4, linear-oblong, ob- 

 tusish, canescent, slightly carinate; achenes densely silky-hirsute. Dry hill- 

 sides: Calif. Utah Ida. B.C. Son. Je-S. 



3. T. linearis Rydb. A low, unarmed shrub; bark of the older stems shin- 

 ing and flaky; leaves linear, white-tomentose, somewhat keeled; bracts of the 

 involucre oblong, acute, white-tomentose, about 8 mm. long; achenes hirsute- 

 villous. Dry hills: Utah Colo. Son. Jl-Au. 



4. T. glabrata A. Gray. Shrub, 3-10 dm. high; primary leaves 6-15 mm. 

 long; secondary ones narrowly linear, spatulate, fleshy, 4-10 mm. long; heads 

 about 12 mm. high; involucres cylindric, 6-7 mm. high, 4 mm. broad, silky- 

 tomentose; achenes densely silky-hirsute. Dry hills: Ore. Ida. Utah Calif. 

 Son. Je-Au. 



5. T. Nuttallii T. & G. Shrub, 3-10 dm. high; primary leaves transformed 

 into spreading subulate spines, 10-18 mm. long; secondary leaves oblanceolate, 

 8-12 mm. long, loosely floccose; heads 10-14 mm. high, fascicled-corymbose; invo- 

 lucres 7-8 mm. high, tomentose; bracts 4, linear-oblong; achenes densely white- 

 hoary. Barren hills: Wyo. Utah. Son. Submont. My-Au. 



6. T. spinosa Hook. & Arn. A divaricately branched shrub, 5-12 dm. high; 

 branches white-tomentose; primary leaves transformed into spines, 5-12 mm. 

 long, usually more or less curved; secondary leaves 5-15 mm. long, linear-clavate, 

 fleshy, glabrous or soon glabrate; heads from the axil of the leaves, 15-18 mm. 

 high; involucres tomentose, about 1 cm. high; bracts oval, obtuse, or some of 

 them acutish. Dry hills and plains: Mont. Colo. Nev. Ore. Plain 'Sub- 

 mont. My-Au. 



7. T. longispina (M. E. Jones) Rydb. Shrub, 1-2 m. high; branches di- 

 varicate, tomentose; primary leaves transformed into slender, straight spines, 

 1.5-3 cm. long; secondary leaves linear-clavate, 10-12 mm. long, glabrate; heads 

 solitary in the axils of the leaves, 12-15 mm. high; involucres about 6 mm. high, 

 tomentose; bracts elliptic; achenes with long white hairs equalling the pappus. 

 T. spinosa longispina M. E. Jones. Alkaline hills: Utah Ariz. Calif. Son. 

 Ap-Jl. 



131. ARCTIUM L. BURDOCK. 



Coarse biennial herbs. Leaves alternate, petioled, with broad cordate or 

 sagittate blades. Heads discoid. Involucres globular; bracts imbricate, in 

 many series, subulate, with hooked tips. Receptacle flat, setose. Flowers 

 hermaphrodite and fertile. Corolla purple or white; tube slender. Anthers 

 sagittate at the base. Achenes oblong, somewhat compressed and 3-angled, 

 truncate. Pappus of numerous short and rigid bristles, falling off separate. 



Involucre less than 2 cm. broad; inner bracts not exceeding the flowers. 1. A. minus. 

 Involucre 2.5 cm. broad or more; inner bracts at least equalling the flowers. 2. A. Lappa. 



1. A. minus Schk. Stem stout, 5-20 dm. high, puberulent, branched; 

 leaves petioled; blades 2-4 cm. long, cordate, repand, grayish tomentulose 

 beneath; heads in a leafy panicle, often with racemiform branches; involucres 

 12-20 mm. high, glabrous; the inner bracts purple-tipped; corollas rose-purple. 

 Lappa minor DC. Waste places: N.S. Ga. Ala. Colo. Ida. B.C.; nat. 

 from Eu. Au-S. 



2. A. Lappa L. Stem 1-2 m. high; leaf-blades thin, broadly ovate-cordate, 

 the lower 4-5 cm. long, grayish tomentose beneath; heads corymbose; involucre 

 glabrous or nearly so; bracts longer and more spreading or reflexed; corollas rose- 

 purple. Waste places: N.B. N.Y. Neb. Minn.; Mont.; nat. or adv. from 

 Eu. Jl-O. 



132. SAUSSUREA DC. 



Perennial herbs. Leaves not spiny, entire or dentate, often somewhat floc- 

 cose. Heads discoid, many-flowered. Involucre usually narrow, turbinate; bracts 

 imbricate in several series. Receptacle flat, fimbrillate or chaffy. Corollas 



