936 CARDUACEAE 



present golden-yellow, equalling the disk; achenes black, tuberculate. Wet 

 places :N.B.Fla. Utah B.C. Plain. Jl-O. 



2. B. vulgata Greene. Annual; stem 5-10 dm. high, glabrous; leaves pin- 

 nately 3-5-foliolate, glabrous or nearly so; leaflets lanceolate, acute, serrate, 

 short-stalked; involucres 10-12 mm. high, 15-25 mm. broad; outer bracts 8-16, 

 linear or linear-oblanceolate, ciliate, entire, rarely exceeding the disk; ligules 

 usually present, equalling the disk; achenes brown or olivaceous, smooth or merely 

 papulose. Wet ground: Ont. N.C. Calif. B.C. Plain. Au-S. 



3. B. comosa (A. Gray) Wiegand. Annual; stem 3-8 m. high, glabrous; 

 leaves simple, 5-10 cm. long, narrowly elliptic or lance-elliptic, acuminate, ser- 

 rate; involucres about 12 mm. high and 12-18 mm. broad; outer bracts 6-8, 

 linear or linear-lanceolate, mucronate, entire, 2-5 times as long as the disk, 

 nearly erect; achenes olive-green or brownish, smooth; awns 3. Wet ground: 

 Mass. Va Colo. Neb. Plain. Au-O. 



4. B. prionophylla Greene. Annual; stem slender, 3-5 dm. high, more or 

 less pubescent; leaves linear or linear-lanceolate, sharply serrate, 5-10 cm. long, 

 sessile; heads nodding, about 1 cm. high, and 2 cm. broad; achenes greenish; 

 awns 3 or 4, very unequal. Water and wet places: Ont. N.Y. S.D. (? Colo.) 

 Mont. Plain. Au-S. 



5. B. glaucescens Greene. Annual; stem 3-7 dm. high, glabrous or spar- 

 ingly hairy; leaves linear-lanceolate, 5-15 cm. long, serrate, sessile, somewhat 

 paler beneath; heads nodding, 1 cm. high, 2-3 cm. wide; ligules often 1 cm. long; 

 awns 4. B. cernua of western reports. In water and wet grounds: Sask. 

 Kans Utah Ida. Alta. Plain Submont. Jl-S. 



6. B. Bigelovii A. Gray. Annual; stem 4-6 dm. high, glabrous or sparingly 

 pubescent; leaves bipinnate, 4-10 cm. long; blades deltoid in outline, primary 

 divisions broadly ovate, the secondary ones oblong or oblong-ovate, obtuse or 

 acutish; involucres about 6 mm. high and 1 cm. broad; outer bracts linear, ob- 

 tuse, shorter than the inner; outer achenes 5-6 mm. long, terete, striate, their 

 awns less than 2 mm. long; central achenes 10-15 mm. long, their awns over 3 

 mm. long. Along streams: Tex. Colo. Ariz. Son. Submont. Jl-S. 



7. B. tenuisecta A. Gray. Annual; stem 3-6 dm. high, branched from the 

 base, glabrous; leaves twice or thrice ternately or pinnately dissected into linear 

 lobes; heads about 1 cm. high and broad; bracts linear, hirsute, the outer usually 

 slightly longer than the inner; achenes glabrous, the outer 6-8 mm. long, the 

 inner 10-12 mm. long; awns fully 3 mm. long, those of the outer achenes shorter. 

 Along streams: Tex. Colo. Ida. Ariz.; Mex. Son. Submont. Au-S. 



80. THELESPERMA Less. 



Glabrous perennial, or annual, with finely dissected or rarely linear entire leaves 

 and long-peduncled heads. Involucre hemispheric or campanulate, of two dis- 

 tinct series of bracts, the outer narrow, short, often spreading, the inner broad, 

 united to about the middle into a cup, their free lobes scarious-margined. Re- 

 ceptacle flat, with a broad, 2-nerved, white-scarious palea subtending each disk- 

 flower. Ray-flowers present, neutral, or none; ligules, if present, yellow, mostly 

 toothed. Disk-flowers perfect, fertile; corolla-tube slender; limb 5-toothed. 

 Anthers obtuse and entire at the base. Style-tips acute. Achenes oblong or 

 linear, terete or slightly compressed. Pappus of 2 retrorsely hispid awns, or 

 sometimes none. 



Heads radiate. 



Leaf-segments linear-filiform, 1 mm. or less wide. 



Annual or biennial; outer bracts subulate-linear, more than half as long as the in- 

 ner. 1. T. trifidum. 

 Perennial from a rootstock; outer bracts linear-lanceolate, half as long as the 



inner or less. 2. T. tenue. 



Leaf-segments linear, over 1 mm. wide; plant perennial or the first only biennial. 

 Plant with a taproot, leafy throughout. 3. T. intermedium. 



Plant with a creeping rootstock or woody caudex, leafy only near the base. 



Involucre not cleft below the middle; throat of the disk-flowers campanulate, 

 shorter than the lobes. 4. T. ambiguum. 



