THISTLE FAMILY 939 



they fall; paleae in a single series surrounding the disk-flowers. Ray-flowers 

 pistillate and sterile; ligules cuneate, 3-cleft. Disk-flowers about 5, hermaphro- 

 dite and fertile. Ray-achenes obovate-oblong or clavate, obcompressed. 



1. L. ramosissima Nutt. Stem 2-8 dm. high, at least diffusely branched, 

 glabrate or slightly pilose when young; lower leaves spatulate, the upper linear 

 or nearly so, softly silky-canescent ; head about 6 mm. high; bracts silky-ciliate ; 

 ligules short, purplish, clavate, carinate along the upper side, about 3 mm. long. 

 Dry ground: Wash. Ida. Nev. Calif. Son. Je-S. 



86. BLEPHARIPAPPUS Hook. 



Annuals, with mostly alternate leaves. Heads radiate. Bracts of the invo- 

 lucre broad, flattened on the back below, with thin, infolded margins, enclosing 

 the ray-achenes; paleae in a series between the disk- and ray-flowers and occa- 

 sionally some among the latter. Ray-flowers 8-20, pistillate and fertile; ligules 

 conspicuous, various-colored. Disk-flowers hermaphrodite and mostly sterile; 

 corollas yellow; lobes pubescent. Achenes of the ray-flowers obcompressed, 

 without pappus. Pappus of the disk-flowers of 5-20 bristles or awns. 



1. B. glandulosus Hook. Annual; stem 1-4 dm. high, diffusely branched, 

 more or less hirsute, glandular at the summit; leaves lanceolate or linear, hirsute, 

 the lower laciniate-pinnatifid or lobed, the upper entire; involucres 7-8 mm. high, 

 12-15 mm. broad; bracts lance-linear, acute, hispidulous and with some black 

 glands below; ligules 8-13, white, about 1 cm. long, 3-lobed; pappus white. 

 Layia glandulosa Hook. & Am. Sandy places: B.C. Ida. w N.M. s Calif. 

 Son. Mr-Je. 



87. PSILOSTROPHE DC. PAPER FLOWER. 



Tomentose or woolly perennial (all ours) or rarely biennial herbs, or low 

 shrubs. Leaves alternate, entire or lobed. Involucre cylindric or campanulate; 

 bracts in a single series, equal, connivent, sometimes with 1-4 scarious ones 

 within; receptacle naked. Ray-flowers few, pistillate and fertile; ligules broad, 

 3-lobed, yellow, becoming papery, persistent. Disk-flowers hermaphrodite and 

 fertile; corollas yellow. Style-branches truncate at the apex. Achenes linear, 

 striate. Pappus of lacerate or ciliate squamellae. [Riddellia Nutt.] 



Stem merely sparingly villous or floccose, not densely white-pannose. 



Squamellae of the pappus one-third as long as the disk-corollas, ovate, mostly ob- 

 tuse; leaves broadly spatulate; ligules 8-12 mm. long, indistinctly nerved. 



1. P. Bakeri. 

 Squamellae of the pappus one-half as long as the disk-corollas, lanceolate, acute or 



acuminate; Ligules 5-8 mm. long, distinctly veined. 



Leaves oblanceolate, loosely villous; heads short-peduncled. 2. P. Tagetinae. 

 Upper leaves linear or linear-oblanceolate, glabrate; heads slender-peduncled. 



3. P. sparsiflora. 

 Stem densely white-pannose. 4. P. Cooperi. 



1. P. Bakeri Greene. Stem much branched, 1-2 dm. high, loosely floccose; 

 basal leaves 5-10 cm. long, petioled; blades spatulate, more or less distinctly 

 3-5-ribbed; involucres 7-10 cm. high and nearly as broad; ligules 5, 10-15 mm. 

 long; achenes glabrous, striate. P. pumila (M. E. Jones) A. Nels. Dry plains 

 and hills: Colo. Utah. Submont. My-Je. 



2. P. Tagetinae (Nutt.) Greene. Stem 1-3 dm. high, diffusely branched, 

 loosely villous; lower leaves spatulate, 2-5 cm. long, entire or lobed; upper leaves 

 narrowly oblanceolate; heads numerous, paniculate; involucres 6-8 mm. high 

 and a little less broad; ligules 3-5, 5-8 mm. long. Riddellia tagetina T. & G. 

 Dry plains: Tex. Colo. Ariz.; n Mex. Son. Je-S. 



3. P. sparsiflora (A. Gray) A. Nels. Stem 1-3 dm. high, green, but spar- 

 ingly hirsute; leaves linear, 5-8 cm. long, usually entire, hirsute; heads corymbose- 

 paniculate; involucres about 6 mm. long, 4-5 mm. wide; ligules usually 3, 7-8 

 mm. long and still broader. R. tagetina sparsiflora A. Gray. Arid places: Ariz. 

 Utah. Son. 



4. P. Cooperi (A. Gray) Greene. Undershrub, 2-5 dm. high; branches 

 densely and finely white-pannose; leaves linear, 2-7 cm. long, tomentose; heads 



