742 



CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



Involucre 5 mm. high or less; leaves pinnat- 

 ifid almost to the midrib, the segments 



very narrow 19. 8. macdougalii. 



Leaves merely toothed or entire. 



Leaves, at least the lower, triangular or tri- 

 angular-cordate; plants usually 1 meter 



high or taller 20. 8. triangularis. 



Leaves not triangular, narrowed at the base; 

 plants lower, seldom more than 30 cm. 

 high. 

 Leaves lanceolate or elliptic, acute, den- 

 ticulate; stems simple 22. 8. crassulus. 



Leaves obovate or oval, obtuse, coarsely 



salient-dentate; stems branched 21. S. carthamoides . 



Upper leaves of the stems much reduced. 

 Rootstock very short, never woody; leaves 

 lanceolate, denticulate; stems stout, 40 cm. 



high or less 23. S. lapathifolius. 



E,ootstocks elongated, horizontal or ascending, 

 woody; leaves various; stems low or tall. 

 Leaves linear, less than 2 mm. wide; plants 



Bmall, usually less than 15 cm. high 24. S. thurberi. 



Leaves 5 mm. wide or more; plants mostly 

 taller. 



Plants glaucous 25. 8. microdot ■tlus. 



Plants not glaucous. 

 Plants tall, stout, 50 cm. high or more; 

 heads very numerous; bracts with 



black tips 26. S. atratus. 



Plants lower, slender, mostly less than 50 



cm. high; heads few; bracts not with 



black tips. 



Leaves and stems permanently floccose. 



All leaves pinnatifid, with toothed 



segments 27. 



Leaves merely coarsely toothed, the 



28. 



S.fendleri. 

 S. canovirens. 

 S. multilobatus . 



segments entire 



Leaves and stems finally glabrate. 



Basal leaves pinnatifid 29. 



Basal leaves not pinnatifid. 

 Leaves very thin, yellowish. 



Basal leaves very deeply cordate, 



with a narrow sinus 30. S. cardamine. 



Basal leaves not deeply or not at 

 all cordate. 



Basal leaves cordate 31. S. pseudaureus. 



Basal leaves not cordate. 

 Basal leaves oblanceolate or 

 elliptic-oblong, attenu- 

 ate at the base, serrate.. 32. S. quaerens. 

 Basal leaves oblong or ovate, 

 not attenuate at the 

 base, crenate 33. S. flavulus. 



