CARDUACEAE. 391 



III. OCCIDENTALES. 



Plant 2-3 dm. high ; stem-leaves obovate or oblong, clasping. 



Plant very leafy ; involucres about 2 cm. broad, short-peduncled or subsessile ; 



achenes strigose. 10. S. carthamoides. 



Plant less leafy; involucres about 15 mm. broad, distinctly peduncled ; achenes 



glabrous. n. S. blitoides. 



Plant about i dm. high; stem-leaves spatulate or ovate, not clasping. 



12. 5". invenustus. 



IV. TRIANGULARES. 



One species. 13- S. triangularis. 



V. SERRAE. 



Heads 12-15 mm. high; disk 8-15 mm. broad; whole plant dark green. 



14. S. admirabilis. 

 Heads 8-10 mm. high; disk 5-6 mm. broad; plant light green. 



15. 5\ serra. 

 VI. CRASSULI. 



Stem-leaves linear or linear-lanceolate. 16. 5". lapathifolium. 

 Stem-leaves ovate or ovate-lanceolate. 



Leaves firm; bracts thick and fleshy. 17. $". crassulus. 



Leaves thin; bracts not very thick. 18. S. semiamplexicaulis. 



VII. RAPIFOLII. 

 One species. 19- S. rapifolius. 



VIII. HYDROPHILI. 



One species. 20. 5". hydrophilus. 



IX. INTEGERRIMI. 



Bracts without black tips; leaves entire-margined. 21. S. integerrimus. 



Bracts usually black-tipped ; leaves more or less dentate or denticulate. 

 Bracts of the involucres narrowly linear-lanceolate, long attenuate. 

 Leaves thick ; basal ones obovate, dentate. 22. S. Hookeri. 



Leaves thin ; basal ones oblanceolate or spatulate, merely denticulate. 



23. S. dispar. 

 Bracts of the involucres linear or oblong, rather abruptly acute, with lanceolate 



or triangular tips. 

 Basal leaf-blades orbicular to broadly oval, rather abruptly contracted into 



the petioles. 24. S. Flintii. 



Basal leaf-blades spatulate to linear-oblanceolate or rarely lanceolate, gradu- 

 ally tapering into the petioles. 

 Inflorescence even in age a flat-topped corymb ; leaves more or less dentate. 



25. 5". coiumbianus. 

 Inflorescence with a short-peduncled terminal head and the lateral ones 



usually very long-peduncled ; leaves merely callous denticulate. 

 Basal leaves thick ; their petioles shorter than the blades. 



26. 5". per plexus. 

 Basal leaves thin ; their petioles usually longer than the blades. 



23. S. dispar. 



X. GLAUCENTES. 



One species. 27. 5". anacletus. 



XL ATRATI. 



Bracts broadly linear, abruptly acute. 28. S. atratus. 



Bracts narrowly linear, long-acute. 29. S. milliflorus. 



XII. CANI. 



Heads 7-8 mm. high. 30. 5". Purshianus. 



Heads i cm. or more high. 31. S. Harbourii. 



