868 CARDUACEAE 



TI. Radxjlae. 



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



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



Leaves not ciliate 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. HUAIILES. 



Leaves all entire; stem very leafy, 4-S 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 



orlmear. IV. Gl.vberrial\e. 



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



Stem-leaves lanceolate. V. Serotixae. 



Stem-leaves obovate. 

 Leaves densely canescent. 

 Bracts not squarrose. 



Lea\es lanceolate; bracts narrowly linear- lanceolate. V. Serotinae. 



Leaves, at least the lower ones, oblanceolate ol* obovate. VII. Incanae. 



Bracts squarrose; leaves numerous, entire, elhpdc. VIII. Wardlvxae. 



I. VlRGA-AtTREAE. 



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



or a few corj^mbose heads. 

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



flowers and pappus; plant 2-3 dm. high. 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. 



Basalleavesbroadly oblanceolate, acute; stem pubescent. 3. S. rubra. 



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



4. S. laevicauUs. 



II. HUillLES. 



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



5. S. decumbens. 

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



Leaves not cihate; bracts oblong; inflorescence usually narrow. 6. S. oreophila. 



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



III. Speciosae. 



One species. 



IV. GX-^BERRHLVE 



8. S. pallida 



9. S. viscidula. 



Heads less than 5 mm. high; stem slender. 



Inflorescence decidedly viscid ; leaves indistinctly triple- veined. 

 Inflorescence not viscid; leaves distinctly triple-veined. 



Plant glaucous; bracts thick, oblong, obtuse. 10. 5. glaucophylla. 



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

 Inflorescence narrow, scarcely secund; bracts linear -lanceolate. 



11. *S. Tnissoiiricnsis. 

 Inflorescence usually open and more or less secund; bracts ' obiong-lanceolkte. 



^ , « ^ , . , 12. iS. glaberrima. 



Heads 6-7 mm. high; stem stout. 13. s. concinna. 



V, Serotinae. 



Inflorescence narrowly rhombic in outline; branches ascending, almost straight, scarcely 

 secund. ^ , , 14. S. elongata. 



Inflorescence broad; branches recm-ved-spreading, distinctly secund. 



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



t-o the marguis and tlie veins. 



Stem usually glabrous up to the inflorescence; leaves glabrous except on the margins 



and on the midveuis. 



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



curved branches. 15. S. serotina. 



\eins of the leaves pubescent below; heads 4-5 mm. high; panicle with long 



branches. 16, s. salebrosa. 



Stem more or less pubescent. 



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



Heads about 4 mm. high; plant comparatively slender. 



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



Leaves glabrous, except the scabrous-cUiolate margins. 



, , , 19. S, serra. 



■ Leaves densely canescent, especially beneath. 



Leaves usuaUy broadly lanceolate. 



Leaves scabrous above. ^ ^ ^ . , 20. S. dumetorum. 



Leaves softly puberulent on both sides. 21 S pruinosa 



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



less yellowish gray. _ 22. S. giivocanescens . 



