240 CARDUACEAE 



Heads subsessile: hairs of the achenes glochidiate-capitellate. 

 Stem-leaves oblanceolate or hnear. 



Pappus of the rays of bristles one-tliird 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. slriqosa. 

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

 flowers all ahke. 14. T. ariznnica. 

 Leaves glabrous or nearly so. 15. T. glabrella 

 Plant acaulescent; heads sessile among the rosulate leaves. 

 Plant not lanate. 



Plant glal)rate, cinereous only when young; leaves oblanceolate or spatulate. 

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



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



Leaves glabrous above. 17. T. Wilcoiiana. 



Leaves strigose on both sides. 



Head 12-15 mm. liigh; pappus ti^ace as long as the achenes; bracts 

 lanceolate. 18. T. intermedia. 



Head less than 1 cm. liigh; pappus a little longer than the achenes; 

 bracts linear. 19. T. leptotes. 



Plant permanently cinereous: leaves linear or linear-oblanceolate. 



20. T. exscapa. 

 Plant lanate. 21. T. spathulata. 



31. BRACHYACTIS Ledeb. 



Bracts oblong or oblong-Unear, obtuse. 1- B. frondosa. 



Bracts narrowly linear, acute. 2. B. angusla. 



32. EREMIASTRUM A. Gray. i. E. bellioides. 



33. LEUCOSYRIS Greene. Spiny Aster. l. L. spinosa. 



34. XYLORRHIZA Nutt. Holly-leaved Aster. 



Leaves not spinulose-toothed. 



Glabrous or nearly so. 1. X. glabriuscula. 



]Slore or less villous. 



Bracts only shghtly unequal, linear-lanceolate. 



LeavesUnear-oblanceolate, acute. 2. X. villosa. 



Leaves spatulate, cuspidate. 3. X. venusta. 



Bracts very unequal, the outer ovate or ovate-lanceolate. 4. X. Parryi. 



Leaves spinulose-toothed. 



Plant 1 dm. or less high, with a short caude.\. 



Ligules S-10 mm. long. 5. X. coloradensis. 



Ligules 15-20 mm. long. 6. X. Brandegei. 



Plant tall, slirubby. 7. X. lanceolata. 



35. HERRICKIA Woot. & Standi. i. H. horrida. 



36. UNAMIA Greene. Sneezewort Aster. 



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



1. U. alba. 

 Inner bracts oblong or elliptic, obtuse or rounded at the apex; hgules yellowLsh, 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. liigh. 1. E. Engelmannii. 

 Leaves lanceolate: heads 8-10 mm. high. 2. E. elegans. 



Bracts firmer, merelv ciliolate. the outer obtuse. 



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

 cidedlv glandular, the leaves lass so. 3. E. wasatchensis. 



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



Inner bracts acute. 4. E. nlaucu%. 



All bracts obtuse or roimded 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, verv unequal, broadly lanceolate, not thick. I. Con'spicui 



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

 late, almost equal in length. 

 Lower leaves petioled. 



Stems stout, 3-5 dm. high, leafj : bracts lanceolate, firm, ascending. 

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



IJ. IXTEGRIFOUl. 



Stem-leaves narrowly linear; disk of heads about 1 cm. broad. 



111. P.\U(rFLOR; 



