384 CARDUACEAE. 



Heads distinctlj' pedicelled, nodding, on lax racemiform branches. 



1 6. A. ptidica. 

 Heads subsessile, conglomerate on short branches. 



Heads 3-4 mm. wide ; flowers dark or purplish brown. 



17. A. rhicomata. 

 Heads 2-3 mm. wide ; flowers light brown. 



Leaves lanceolate. 18. A. gnaphaloides. 



Leaves linear or nearly so. 19. A. pahularis. 



VL DiVERSIFOLIAE. 



Leaves in age greenish and more or less glabrate above. 



Lower leaves more or less cuneate-oblanceolate, lobed above the middle with 

 lanceolate lobes ; upper leaves entire ; plant usually cespitose. 



20. A. ludoviciana. 

 Leaves nearly all deeply pinnatifid, with linear or linear-lanceolate lobes. 



21. A. Uiidcrwoodii. 

 Leaves permanently and almost equally white-tomentose on both sides. 



Lower leaves cuneate or cuneate-oblanceolate, 3-lobed (more seldom 5-lobed) 



above the middle with lanceolate lobes. 22. A. Brittonii. 



Lower leaves deeply pinnatifid with long linear or linear-lanceolate lobes. 



23. A. diversifolia. 

 VH. Stenophvi.lae. 



Leaves in age glabrate above : inflorescence lax. 



Heads erect ; divisions of the leaves filiform. 24. A. Wriglitii. 



Heads nodding ; divisions of the leaves narrowly linear. 



25. A. Bakeri. 

 Leaves permanently white-tomentose on both sides ; heads crowded. 



Leaves, at least the lower ones, with linear rather short divisions. 



26. A. coloradensis. 

 Leaves with filiform divisions. 27. A. kansana. 



VHL VULGARES. 



Divisions of the leaves broad, lanceolate or oblong. 



Leaves, except the uppermost, twice pinnatifid with obtusish lobes, glabrous 



or minutely appressed canescent beneath. 28. A. fraserioides. 



Leaves, except sometimes the lowermost, once pinnatifid, with acute or acutish 

 lobes, or the upper entire, white-tomentose beneath. 

 Tall, 6-10 dm. high; upper leaves entire; the rest simply pinnatifid. 



29. A. elatior. 

 Lower, 2-6 dm. high ; all leaves pinnatifid ; the lower often twice pinnatifid. 



30. A. incouipta. 

 Divisions of the leaves narrowly linear-lanceolate or linear. 



21. A. discolor. 



IX. BiGELOVIANAE. 



One species. 32. A. Bigelovii. 



X. Tridentatae. 



Leaves nearly all trifid or tridentate at the apex. 



Divisions of the leaves mostly long, narrowly linear, sometimes almost filiform; 



heads about 2 mm. wide. 33. A. fripartita. 



Divisions or teeth of the leaves short, ovate or oblong. 

 Heads 2-2 mm. wide. 



Bracts densely tomentose ; inflorescence rather congested. ^ 



Shrub tall ; inflorescence much branched ; heads about 2 mm. wide. 



34. A. tridentata. 

 Shrub dwarf ; inflorescence rather simple and spike-like ; heads 3 mm. 

 wide. 35. A. arbtiscula. 



Bracts of the involucres almost glabrous ; inflorescence lax, racemiform. 



36. A. nova. 



