922 CARDUACEAE 



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



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



with brownish, rose, or yellow; plants mostly tall 

 Leaves tomentose on both sides; plants little if at all glandular; involucres tomen- 



tose at the base. 

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



Perennial or biennial; stem 3-5 dm. high; 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 56 mm. high, numerous, in glomerules ending the short spread- 

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

 leaves lanceolate or oblong, with rounded bases, cuspidate. 



3. G. proximum. 

 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 linear, merely acute or obtuse. 

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



4. G. sulphur escens. 

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



5. G. lagppodloides. 

 Leaves distinctly decurrent; bracts acutish; heads 45 mm. high. 



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

 Bracts lance-ovate; inflorescence narrow. 7. G. microcephalum. 



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



glabrous. 8. G. Macounii. 



Heads leafy-bracted; involucral bracts little 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. uliginosum, 



Upper leaves narrowly linear. 11. G. exili folium. 



Stem mostly simple, erect; glomerules spicately disposed. 



12. G. Grayi. 



Bristles of the pappus united 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. albatum Osterh. Dry grounds: Colo. N.M. Calif. Submont. Au-O. 



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. proximum 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 yellowish 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-album Hook., not L. Wet sandy soil: 

 Mont. Tex. N.M. Wash. Jl-N. 



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

 about 1 dm. high, densely woolly-tomentose; 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 



