834 CARDUACEAE 



Tribe 3. ASTEREAE. 

 A. Plants not dioecious. 



I. Marginal pistillate flowers, if present, ligulate. 

 a. Ray-flowers yellow or none. 



1. Pappiis of scales or awns or lacking, never of numerous capillary bristles. 



a. Bracts not conspicuously scarious-margined. 



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

 paleaceous. 

 Disk-flowers usually fertile; leaves linear to filiform. 



7. GUTIERREZIA. 



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



8. Amphip.vppus. 

 Heads large, many-flowered; involucre in all except one species v-iscid. 



Involucres hemispherical; pappus of a few deciduous awns. 



9. Grindell\. 

 Involucres turbinate; pappiis of persistent linear, very acute paleae. 



10. V.^AXLEVE.^.. 



b. Bracts with conspicuous scarioiis flmbriate margios. 



11. ACAJIPTOPAPPUS. 



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



o. 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-punctate. 13. Ericameria. 



Leaves not restnous-pimctate. 



Involucres narrowly turbinate, its bracts more or less charta- 

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

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

 form. 14. Chrysothamntjs. 

 Involucres broadly turbinate to hemispheric, its bracts more or 

 less imbricate, but not in deflinite 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 well imbricate or 

 both. 

 Achenes trxmcate at the top, gradually tapering towards 

 the base, usually cinereous-pubescent ; bracts neither 

 broad nor abruptly acuminate. 

 Appendages or tips of the style-branches flUform; 

 undershrubs with white-tomentulose stems and 

 glandular-hairy foUage; leaves entire-margined. 



21. Macroxema. 

 Appendages or tips of the style-branches subulate to 

 ovate. 

 Leaves with spinulose-tipped teeth; corolla-tube 

 slender. (Rayless species of) 



17. Sideranthtjs. 

 Leaves not spinulose; corolla-tube dilated above. 



15. ISOCOM.^.. 



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

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

 hairy: bracts of the involucres broad and abruptly 

 aciuninate; appendages of the style-branches ovate to 

 short-subulate. 20. Oonopsis. 



Heads radiate. 



Rays scarcely longer than the disk-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 rmg; annuals, 

 equally leafy throughout; bracts more or less fohaceous. 



16. Pkioxopsis. 

 Pappus persistent. 



Bracts chartaceous, not foliaceous, merely -with a green 

 tip; plants annual, or perennial with a caudex, equally 

 leafy throughout; pappus in age more or less spread- 

 ing; achenes turbinate and densely silky. 



17. Sider.\xthxjs. 

 Bracts more or less foliaceous, at least above; plants 



perennial with taproots, large basal leaves, and few 

 and rather small stem-leaves; pappus not spreading; 

 achenes oblong, glabrous or sparingly pubescent. 



18. Pyrrocoinlv. 

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



Bracts not longitudinally striate. 



Shrubs with glandular-punctate leaves. 



Heads large, solitary; involucral bracts in about 2. 

 series; rays numerous. 19. Stenotopsis. 



