850 CARDUACEAE 



Leaves oblong or lanceolate, decidedly acute, those subtending the 



heads narrowly linear. 4. C. foliosa. 



Leaves oblanceolate or obovate. those of the inflorescence elliptic or 



oval. 

 Disk of the heads about 15 mm. broad; leaves strigose. 



Inner bracts with subulate, usually brownish and spreading tips. 



5. C. caudata. 



Inner bracts merely acute. 6. C. amplifolia. 



Disk of the heads 1012 mm. broad; leaves hirsutulous. 



7. C. imbricata. 

 Heads peduncled, naked or rarely subtended by one small leaf. 



Plant less than 1 dm. high; heads solitary at the ends of the branches. 



8. C. depressa. 

 Plant 2-3 dm. high; heads more or less corymbose. 



Heads long-peduncled ; peduncles 2-7 cm. long. 9. C. pedunculata. 



Heads short-peduncled. 



Plant finely silvery-canescent, scarcely at all hirsute. 



10. C. mollis. 

 Plant usually grayish-green, conspicuously hirsute on the stem; leaves 



hirsute-ciliate towards the b*se. 

 Most of the leaves sessile. 



Leaves oblanceolate or obovate, obtuse or merely apiculate; disk 



of the heads 15-20 mm. broad. 11. C. villosa. 



Leaves narrowly oblanceolate, decidedly acute; disk 10-12 mm. 

 broad. 12. C. hirsutissima. 



Most of the leaves distinctly petioled; disk 10-12 mm. broad. 



Involucre more than 1 cm. high and broad; leaves oblanceolate. 



13. C. Bakeri. 

 Involucre scarcely 1 cm. high and broad; leaves linear-oblance- 



olate. 14. C. floribunda. 



Involucre hirsute or both hirsute and resinous-granuliferous. 



Leaves lanceolate, acute or acuminate, sessile; plant densely hirsute with long 



white hairs. 15. C. barbata. 



Leaves oblanceolate, oblong, obovate or oval; plant not conspicuously long-hairy. 

 Involucre densely hirsute, scarcely at all resinous-granuliferous. 



Leaves short, 1-2 cm. long, obovate, nearly all sessile. 16. C. Butleri. 

 Leaves oblanceolate, the lower petioled. 



Plant 1-2 dm. high; heads usually solitary and sessile. 



17. C. pumila. 

 Plant 23 dm. high; heads peduncled and corymbose. 



Disk of the heads 8-10 mm. broad; leaves densely hirsute, not 



resinous, only the lower petioled. 18. C. columbiana. 



Disk of the heads 12-18 mm. wide; leaves distinctly resinous-granu- 

 liferous, nearly all petioled. 19. C. grandis. 

 Involucre sparingly hirsute, copiously resinous-granuliferous. 



Upper leaves obovate, oval, only rarely oblong or broadly oblanceolate, 



sessile. 

 Heads sessile, subtended by oblong or obovate leaves. 



Leaves numerous, ascending, 3-5 cm. long; involucre about 1 cm. 



high. 20. C. resinolens. 



Leaves scattered, spreading, 1-2 cm. long; involucres 8-9 mm. high. 



21. C. fulcrata. 

 Heads peduncled, naked or subtended by small linear leaves. 



Leaves densely hispid, not conspicuously granuliferous. 



22. C. horrida. 

 Leaves conspicuously granuliferous, only sparingly hispidulous. 



23. C. viscida. 

 Upper leaves as well as the lower oblanceolate, most of them petioled. 



Leaves broadly oblanceolate; heads peduncled. 

 Leaves decidedly hairy, sparingly granuliferous. 



Stem simple to near the top. 24. C. asprclla. 



Stem profusely branched. 14. C. floribunda. 



Leaves sparingly hairy, conspicuously granuliferous. 



25. C. hispida. 

 Leaves narrowly linear-oblanceolate; heads subsessile. 



26. C. stenophylla. 



Heads discoid; leaves lanceolate, hispid-ciliate, otherwise glabrous, minutely granu- 

 liferous. 27. C. oregana. 



1. C. angustifolia Rydb. Stems erect, 2-4 dm. high, canescent and more 

 or less hirsute; leaves 2-5 cm. long, 2-5 mm. wide, acute, grayish-strigose, his- 

 pid-ciliate; involucres turbinate-campanulate, 8-10 mm. high; bracts narrow and 

 linear, acute; ligules about 1 cm. long. C. stenophylla Britt. & Brown, not Greene. 

 Sandy places: Alta. Kans. Plain. Au-S. 



2. C. caespitosa M. E. Jones. Cespitose from a woody root, forming a 

 mat; stems spreading, 5-8 cm. long, villous-hirsute; leaves spatulate, villous- 

 canescent, apiculate; heads sessile; involucres 6 mm. high; bracts ashy-strigose, 



