240 



CARDUACEAE 



Heads subsessile; hairs of the achenes glochidiate-capitellate. 

 Stem-leaves oblanceolate or linear. 



Pappus of the rays of bristles one-third to one-half as long as 

 those of the disk-flowers; ray-flowers glandular-puberulent 

 outside. 13. T. incana. 



Pappus of the rays reduced to a crown of short squamellae; ray- 

 flowers glabrous. 10. T. strigosa. 

 Leaves all decidedly spatulate; pappus-bristles of ray- and disk- 

 flowers all alike. 14. T. arizonica. 

 Leaves glabrous or nearly so. 15. T. glabrella. 

 Plant acaulescent; heads sessile among the rosulate leaves. 

 Plant not lanate. 



Plant glabrate, cinereous only when young; leaves oblanceolate or spatulate. 

 Bracts obtuse; ray-flowers with very short pappus. 16. T. Bothrockii. 



Bracts acute ; pappus of disk- and ray-flowers alike, of long bristles. 



Leaves glabrous above. 17. T. Wilcoxiana. 



Leaves strigose on both sides. 



Head 12-15 mm. high; pappus twice as long as the achenes; bracts 

 lanceolate. 18. T. intermedia. 



Head less than 1 cm. high; pappus a httle longer than the achenes; 

 bracts linear. 19. T. leptotes. 



Plant permanently cinereous; leaves linear or linear-oblanceolate. 



20. T. exscapa. 

 Plant lanate. 21. T. spaihulata. 



31. BRACHYACTIS Ledeb. 



Bracts oblong or oblong-Unear, obtuse. 

 Bracts narrowly linear, acute. 



32. EREMIASTRUM A. Gray. 



33. LEUCOSYRIS Greene. Spiny Aster." 



34. XYLORRHIZA Nutt. Holly-leaved Aster. 



Leaves not spinulose-toothed. 

 Glabrous or nearly so. 

 More or less villous. 



Bracts only sUghtly unequal, linear-lanceolate. 

 Leaves linear-oblanceolate. acute. 

 Leaves spatulate, cuspidate. 

 Bracts very unequal, the outer ovate or ovate-lanceolate. 

 Leaves spinulose-toothed. 



Plant 1 dm. or less high, with a short caudex. 

 Ligules 8-10 mm. long. 

 Ligules 15-20 mm. long. 

 Plant tall, shrubby. 



35. HERRiCKIA Woot. & Standi. 



5. X. coloradensis. 



6. X. Brandegei. 



7. X. lanceolate. 



1. H. horrida. 



36. UNAMIA Greene. Sneezewort Aster. 



Inner bracts ovate-lanceolate, acute, the outer lance-subulate; ligules white. 



1. V. alba. 

 Inner bracts oblong or elliptic, obtuse or rounded at the apex; ligules yellowish, the 

 outer lanceolate, obtusish. 2. U. lutescens. 



37. BUCEPHALUS Nutt. 



Bracts all thin and acute, villous-ciUate on the margins; style-appendages subulate. 

 Leaves ovate-oblong or broadly lanceolate; heads 10-15 mm. high. 1. E. Engelmannii. 

 Leaves lanceolate; heads 8-10 mm. high. 2. jE. elegans. 



Bracts firmer, merely ciliolate. the outer obtuse. 



Bracts with more or less foliaceous tips; involucre and branches of inflorescence de- 

 cidedly glandular, the leaves less so. 3. E. wasatchcnsis. 

 Bracts without foliaceous tips; plant not glandular or very rarely so. 



Inner bracts acute. 4. E. nlaucus. 



All bracts obtuse or rounded and mucronate at the apex. 5. E. formosus. 



38. ASTER (Tourn.) L. Aster. 

 Involucres and peduncles glandular. 



Leaves ovate, oval, or the lower obovate, sharply and coarsely serrate; bracts well 



imbricate, very unequal, broadly lanceolate, not thick. I. Conspicui. 



Leaves lanceolate, oblong, or Unear, entire or, if sUghtly toothed, bracts linear-lanceo- 

 late, almost equal in length. 

 Lower leaves petioled. 



Stems stout, 3-5 dm. high, leafy; bracts lanceolate, firm, ascending. 

 Stem-leaves lanceolate to ovate: disk of heads 1.5-2 cm. broad. 



, ,. II. INTEGRIFOLII. 



stem-leaves narrowly Imear; disk of heads about 1 cm. broad. 



III. P.\UCIFLORI. 



