CARDUACEAE. 353 



VI. MULTIFLORI. 



Pubescence of the stem spreading or reflexed. 



Heads less than 5 mm. high. 14- A. exiguus. 



Heads 6-8 mm. high. 15- A. crassnlus. 



Pubescence of the stem appressed or ascending. 



Bracts very unequal in length, well imbricated, the outer much shorter. 

 Bracts narrowly oblanceolate, acutish, especially the inner. 



1 6. A. multiflorus. 

 Bracts broadly oblanceolate or the outer spatulate, very obtuse. 



17. A. polycephalus. 

 Bracts almost equal in length or the outer sometimes longer ; heads few or 



solitary at the ends of the branches. 

 Bracts thick, very squarrose ; leaves thick, densely strigose. 



1 8. A. cornmutatus. 

 Bracts thin, not squarrose ; leaves sparingly strigose, in age often glabrate. 



19. A. falcatus. 



VII. SAGITTIFOLU. 



One species. -20. A. Lindleyanus. 



VIII. LAEVES. 



Green tips of the bracts broadly rhombic ; leaves of the branches much reduced. 



21. A. laevis. 



Green tips of the bracts narrowly rhombic or rhombic-oblanceolate ; leaves of 

 the branches gradually but not conspicuously reduced. 22. A. Geyeri. 



IX. PORTERIANI. 



One species. 23. A. Porteri. 



X. SUBRACEMOSI. 



Inflorescence falsely racemose ; leaves linear to oblanceolate. 



24. A. subracemosus. 



XI. SALICIFOLII. 



Inflorescence elongated, not flat-topped. 



Heads numerous in a much branched panicle ; bracts not with white mid-ribs. 

 Leaves distinctly toothed. 



Disk of the head about i cm. high and broad ; leaves thickish. 



25. A. salicifolins. 

 Disk 6-8 mm. high and broad; leaves thin. 26. A. paniculatus. 



Leaves entire, rarely denticulate. 



All bracts narrowly linear ; branches ascending ; rays purplish. 

 Bracts almost linear-filiform, more or less squarrous. 



27. A. hesperius. 



Bracts linear, erect. 28. A. coerulescens. 



Outer bracts broader than the inner, oblanceolate ; branches more di- 

 vergent. 



Rays usually white. 29. A. Osterhoutii. 



Rays purple. 30. A. fiuviatilis. 



Heads fewer; bracts with white mid-ribs. 31. A. laetevirens. 



Inflorescence more or less flat-topped. 



Leaves lanceolate to linear-lanceolate, firm ; heads numerous. 



32. A. corymbiformis. 

 Leaves narrowly linear, thin ; heads few. 33. A. longulus. 



XII. LOXCHOPHYLLI. 



One species. 34- A. lonchophylhts. 



XIII. OCCIDENTALES. 



One species. 35- A. Fremontii. 



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