922 CARDUACEAE 



Bristles of the pappus not united at the base, falling off separately. 



Heads not leafy-bracted ; involucral bracts well imbricate, scarious, white or tinged 

 with brownish, rose, or yellow; plants mostly tall. 

 Leaves tomentose on both sides; plants Uttle if at aU glandular; involucres tomen- 

 tose at the base. 

 Stem-leaves narrowed at the base, neither decurrent nor clasping. 



Perennial or biennial; stem 3-5 dm. liigh; inflorescence open; bracts white. 



1. G. Wrightii. 

 Annual; stem 1-2 dm. high; inflorescence dense; bracts yellowish. 



2. G. thermale. 

 Stem-leaves not narrowed at the base, more or less decurrent, or at least 



auricled-clasping. 

 Leaves with short broad adnate auricles at the base; bracts obtuse. 



Heads 5-6 mm. high, nimierous, in glomerules ending the short spread- 

 ing branches; bracts sUghtly if at all yellowish; plant tall; stem- 

 leaves lanceolate or oblong, with rounded bases, cuspidate. 



3. G. proxirnum. 

 Heads 4 mm. high, few, in small glomerules, ending the stem or few 



erect branches; bracts decidedly yellowish when young; plant low; 

 leaves oblong to hnear, merely acute or obtuse. 

 Stem erect, strict; lower stem-leaves oblong-oblanceolate. 



4. G. sulphurescens. 

 Stem decumbent at the base; lower stem-leaves spatulate. 



5. G. lagopodioides. 

 Leaves distinctly decurrent; bracts acutish; heads 4—5 mm. high. 



Bracts broadly ovate; inflorescence corymbiform. 6. G. Williamsii. 

 Bracts lance-ovate; uiflorescence narrow. 7. G. microccphalum. 



Leaves on the upper surface green and decidedly glandular, decurrent; involucres 

 glabrous. 8. G. Macounii. 



Heads leafy-bracted; involucral bracts httle imbricate, brown or greenish; plant low; 

 involucre floccose at the base. 

 Plants loosely floccose; leaves broad, spatulate, oblong or oblanceolate. 



9. G. palustre. 

 Plants appressed-tomentose ; leaves except the lowest narrowly oblanceolate or 

 linear. 

 Stem diffusely branched; glomerules crowded, cymosely disposed. 



Upper leaves narrowly oblanceolate. 10. G. iiliginosum. 



Upper leaves narrowly Linear. 11. G. exilifolium. 



Stem mostly simple, erect; glomerules spicately disposed. 



12. G. Grayi. 

 Bristles of the pappus imited in a ring at the base and falling off together; leaves ob- 

 lanceolate or spatulate. 13. G. ustulatum. 



1. G. Wrightii A. Gray. Biennial or perennial, with a taproot; stem up- 

 right, much branched above, white-floccose throughout; leaves oblanceolate or 

 spatulate, 2-4 cm. long, the uppermost linear; heads numerous in a rather open 

 panicle; involucres 5-6 mm. high; bracts white, oblong, abruptly pointed, pearly 

 white. G. albalum Osterh. Dry grounds: Colo. — N.M. — Calif. Submont. Au-0. 



2. G. thermale E. Nels. Annual; stem low, branched from the base, 

 grayish-tomentose ; basal leaves oblanceolate, about 3.5 cm. long; stem-leaves 

 narrowly oblanceolate to linear, 1-3 cm. long; heads sessile in small glomerules, 

 terminating the branches; involucres 4-5 mm. high; bracts dull white or yellow- 

 ish, the outer ovate, the innermost linear, abruptly apiculate. G. Wrightii Coult. 

 & Nels., not A. Gray. Hot-spring formations: n Wyo. Mont. Jl. 



3. G. proxirnum Greene. Biennial or annual, with a taproot, branched at 

 the base; stem 3-6 dm. high, very leafy; basal leaves spatulate or oblanceolate, 

 3-4 mm. long; inflorescence closely paniculate, leafy-bracted; involucres villous, 

 5-6 mm. high; bracts straw-colored or ochroleucous, obtuse. Perhaps scarcely 

 distinct from G. Chilense Spreng. Wet places: Wyo. — Utah — Nev. — Wash. 

 Submont. — Mont. Jl-Au. 



4. G. sulphurescens Rydb. Annual or biennial; stem usually simple. 

 2-4 dm. high, often j'cllowish above; basal leaves spatulate, 2-3 cm. long, white- 

 woolly; stem-leaves linear or the lower oblong-spatulate, mostly erect; heads 

 sessile in small glomerate cymes; involucres 4-5 mm. high; bracts elliptic or oval, 

 very obtuse, yellow, glossy. G. luteo-albutn Hook., not L. Wet sandy soil: 

 Mont.— Tex.— N.M.— Wash. Jl-N. 



5. G. lagopodioides Rydb. Biennial, usually branched at the base; stem 

 about 1 dm. higii, densely woolly-tonientose ; basal leaves spatulate, 1-1.5 cm. 

 long, loosely woolly ; stem-leaves oblong-spatulate or the lower obovate-spatulate ; 

 heads in small conglomerate cymes; involucres about 4 mm. high; bracts oblong 



