868 CARDUACEAE 



Bracts of the inflorescence lanceolate or linear-lanceolate, acute or acuminate. 



Leaves ciliate at the base. I. Virga-Aureae. 



Leaves not ciUate at the base. IV. Glaberrimae. 



Bracts of the inflorescence oblong or linear-oblong, obtuse. 



Leaves, at least the basal ones, toothed; stem-leaves few; plants 1-4 dm. high. 



II. HUMILES. 



Leaves all entire; stem very leafy, 4-8 dm. high. III. Speciosae. 

 Leaves triple- veined ; heads more or less secund, on recurved-spreading branches 

 (except usually in Nos. 9 and 11). 

 Plants slender, not very leafy, 2-4 dm. high; stem-leaves narrowly oblanceolate 



or linear. IV. Glabehrimae. 

 Plant tall, leafy, 4-10 dm. high. 



Stem-leaves lanceolate. V. Serotinae. 



Stem-leaves obovate. VI. Radul.'^e. 

 Leaves densely canescent. 

 Bracts not squarrose. 



Lea\es lanceolate; bracts narrowly linear-lanceolate. V. Serotin.\E. 



Leaves, at least the lower ones, oblanceolate oi" obovate. VII. Incanae. 



Bracts squarrose; leaves numerous, entire, elUpdc. VIII. Wardianae. 



I. VraCA-AlIREAE. 



Plants low and slender, 1-3 dm. high; inflorescence corymbiform; branches with a single 



or a few corymbose heads. 

 Heads 7-9 mm. high; inner bracts linear-lanceolate, of about the same length as the 



flowers and pappus; plant 2-3 dm. liigh. 1. S. scopulorum. 



Heads 5-7 mm. high; bracts lanceolate, the inner shorter than the flowers and the 



pappus; plant usually less than 2 dm. high. 2. S. ciliosa. 



Plants stout, 3-4 dm. high; inflorescence paniculate, but narrow; branches racemiform; 



heads 7-9 mm. liigh. 

 Basal leaves broadly oblanceolate, acute; stem pubescent. 3. S. rubra. 



Basal leaves narrowly oblanceolate, obtuse; stem glabrous tip to the inflorescence. 



4. S. laevicaulis. 

 II. HtnviiLES. 



Plant low, 1-1.5 dm. high; inflorescence with few heads, short, congested. 



5. S. decumbcns. 

 Plant taller, 2-4 dm. high; inflorescence with many heads, elongate. 



Leaves not cUiate; bracts oblong; inflorescence usually narrow. 0. S. oreophila. 

 Leaves ciUate at the base; bracts Unear; inflorescence open. 7. S. dilatata. 



III. Speciosae. 

 One species. 8. S. pallida. 



IV. Glaberrimae. 



Heads less than 5 mm. high; stem slender. 



Inflorescence decidedly viscid; leaves indistinctly triple- veined. 9. S. viscidula. 

 Inflorescence not viscid; leaves distinctly triple-veined. 



Plant glaucous; bracts thick, oblong, obtuse. 10. S. glaucophylla. 



Plant not glaucous; bracts not thick, linear-lanceolate to oblong-lanceolate. 

 Inflorescence narrow, scarcely secund; bracts Unear-lanceolate. 



11. S. 7nissouriensis. 

 Inflorescence usually open and more or less secund; bracts oblong-lanceolate. 



12. S. (jlaberrima. 

 Heads G-7 mm. liigh; stem stout. 13. S. concinna. 



V. Serotinae. 



Inflore-scence narrowly rhombic in outline; branches ascending, almost straight, scarcely 



secund. 14. S. elongata. 



Inflorescence broad; branches recurved-spreading, distinctly .secund. 



Leaves green, sparingly pubescent or glabrous; pubescence scabrous, mostly confined 

 to the margins and the veins. 

 Stem usually glabrous u]> to the inflorescence; leaves glabrous except on the margins 

 and on Uw niidvcins. 

 Veins of the leaves glabrous; heads 5-6 mm. liigh, in a short panicle with strongly 



curved branches. 15. S. serotina. 



Veins of the leaves pubescent below; heads 4-5 mm. liigh; panicle with long 

 branches. 16. S. salcbrosa. 



Stem more or less pubescent. 



Heads 5 mm. or more high; leaves pubescent. 17. S. polyphylla. 



Heads about 4 mm. liigh; plant comparatively slender. 



Leaves pubescent, at least on the veins. 18. S. canadensis. 



Leaves glabrous, except the scabrous-ciUolate margins. 



19. S. serra. 

 Leaves densely canescent, especially beneath. 

 Leaves usuaUy broadly lanceolate. 



Leaves scabrous above. 20. S. dumetorum. 



Leavas softly i)ubcrulent on both sides. 21. S. pruinosa. 



Leaves Unear-lanceolate, finely and rather softly canescent on both sides, more or 

 less yellowish gray. 22. S. gilvocanescens . 



