834 CARDUACEAE 



Tribe 3. ASTEREAE. 

 A. Plants not dioecious. 



I. Marginal pistillate flowers, if present, lignlate. 

 a. Ray-flowers yellow or none. 



1. Pappus of scales or a^vns or lacking, never of numerous capillary bristles. 



a. Bracts not conspicuously scarious-margined. 



Heads small, not over 4 mm. high, few-flowered; pappus more or less 

 paleaceous. 

 Disk-flowers usually fertile; leaves linear to flUform. 



7. GUTIERREZIA. 



Disk-flowers sterile; leaves short, obovate or spatulate. 



8. Amphipappus. 

 Heads large, many-flowered; involucre Ln all except one species viscid. 



Involucres hemispherical; pappus of a few deciduous awns. 



9. Grixdell\. 

 Involucres turbinate ; pappus of persistent Unear, very acute paleae. 



10. Vanclevea. 



b. Bracts with conspicuous scarious fimbriate margins. 



11. Ac.^ilPTOPAPPUS. 



2. Pappus at least in part of numerous capillary bristles. 



a. Pappus double, the inner of capillary bristles, the outer of paleae or 

 short bristles; involucres many-flowered, hemispherical with narrow 

 imbricated bracts. 12. Chrtsopsis. 



b. Pappus wholly of capillary bristles. 



Heads discoid. 



Leaves resinous-pimctate. 13. Ericamerl\.. 



Leaves not resinous-punctate. 



Involucres narrowly turbinate, its bracts more or less charta- 

 ceous, keeled, arranged in definite (usually .5) vertical ranks; 

 achenes elongate-Unear ; tips of style-branches subulate-fili- 

 form. 14. Chrysothamnus. 

 Involucres broadly tiu-binate to hemispheric, its bracts more or 

 less imbricate, but not in definite vertical ranks ; achenes 

 scarcely elongate-Unear. 

 Style-tips obtuse; involucral bracts narrow and poorly im- 

 bricate. (Rayless species of) 45. Erigeron. 

 Style-tips acute; bracts either broad or weU imbricate or 

 both. 

 Achenes truncate at the top, gradually tapering towards 

 the base, usually cinereous-pubescent ; bracts neither 

 broad nor abruptly acuminate. 

 Appendages or tips of the st.yle-branches flUform; 

 underslirubs with wliite-tomentulose stems and 

 glandiflar-hairy foUage; leaves entire-margined. 

 21. IMacronema. 

 Appendages or tips of the style-branches subulate to 

 ovate. 

 Leaves with splnulose-tipped teeth; corolla-tube 

 slender. (Rayless species of) 



17. Siderantiius. 

 Leaves not spinulose; corolla-tube dilated above. 



15. ISOCOMA. 



Achenes elongato-obovoid, i. e., tapering at both ends, 

 but more so below, multi-striate, glabrous or sUghtly 

 liairy; bracts of the involucres broad and abruptly 

 acuminate ; appendages of the style-branches ovate to 

 short-subulate. 20. OoNOPsis. 



Heads radiate. 



Rays scarcely longer tlian the di.sk-flower. 18. Pyrrocoma. 

 Rays conspicuous, much exceeding the disk. 



Leaves pinnate or toothed; lobes or teeth spinulose-tipped. 

 Pappus of the fertile achenes deciduous in a ring; annuals, 

 equally leafy throughout; bracts more or less foliaceous. 



16. PRIONOP.SIS. 



Pappus persistent. 



Bracts chartaceous, not foliaceous, merely with a green 

 tij); i)lant.s annual, or perennial with a caudex, equally 

 leafy tliroughout; pappus in age more or less spread- 

 ing; achenes turbinate and densely silky. 



17. SlOER.\NTHUS. 



Bracts more or loss foliaceous, at least above; plants 

 jxTcniiial with tajn-oots, large basal leaves, and few 

 and rather small sdiii-loaves; pap])us not spreading; 

 achenes oblong, glabrous or sparingly pubescent. 



18. Pyrrocoma. 

 Leaves entire or toothed, but teeth not spinulose-tipped. 



Bracts not longitudinally striate. 



Shrubs with glandular-i)imctate leaves. 



Heads large, solitary; involucral bracts in about 2; 

 series; rays numerous. 19. Stenotopsis. 



