COMPOSITAE 193 



Involucral scales with spreading tips. 1. S. petiolaris. 



Involucral scales appressed. 



Heads in axillary clusters. 2. 8. flexicaulia. 



Heads in a terminal corymb. 3. S. rigida. 



Heads paniculate. 



Leaves not strongly 3-nerved. 

 Panicle branches ascending. 



Lower leaves ovate. 4. S. speciosa. 



Lower leaves lanceolate. 5. S. rigidiuscula. 



Panicle branches recurved-spreading. 



Stems glabrate or sparingly hairy. 6. S. tdmifoUa. 



Stems strongly hairy. 7. S. rugosci. 



Leaves strongly 3-nerved. 

 Stems glabrous. 



Branches of panicle puberulent. 8. S. serotina. 



Branches of panicle glabrous. 9. S. Missoiiriensis. 



Stems pubescent or scabrous. 



Leaves sharply sei rate to entire. 10. S. Canadensis. 



Leaves crenate to entire. 



Heads 2\^' high. 11. S. nemoraUs. 



Heads 3^^ high. 12. S. longipetiolata, 



1. S. petiolaris Ait. l°-3° high, pubescent : leaves oblong-lanceolate, 

 short-petioled, sharply serrate : heads 3'^-4^^ liigh, in a compound thyrse: 

 rays about ten. — Abundant in a rocky wood, just north of Roanoke, Kan- 

 sas City. August-September. 



2. S. flexicaulis L. Stems l°-3° high, glabrous, zigzag : leaves ovate, 

 petioled, sharply serrate : heads 3'^ high : rays 3 or 4. — In rich woods 

 around Sibley. Local. August-September. 



3. S. rigida L. 2°-5° high, roughish-pubescent : leaves oblong-ovate, 

 thick, serrulate, the lower petioled, the upper sessile : heads ¥'-b" high : 

 rays 6-10. — Not uncommon in dry soil, especially in the southern part. 

 August-September. 



4. S. speciosa Nutt. 2°-5° high, glabrous : leaves ovate, serrulate, 

 petioled : heads 3^^-4^^ liigli) very numerous in a large compound thyrse : 

 rays about five. — Abundant locally in the bluffs east of Dodson ; also 

 north of Lee's Summit. Very handsome. September-October. 



5. S. rigidiuscula (T. & G. ) Porter. Like the last but leaves nar- 

 rower : thyrse narrower and less branching, l''-3'' wide, 3''-6'' long. — 

 Found on the prairies near Buckner, and as a waif near Dodson. Sep- 

 tember-October. 



6. S. ulmifolia Muhl. Stem l°-4° high, smooth or slightly pubescent : 

 leaves thin, oblong-ovate, often A'-b^ long, sharply serrate, somewhat 

 rough above, petioled, hairy : heads 2''^-3^'' high : rays about four. — 

 Abundant in dry woods throughout. August-October. 



7. S. rugosa Mill. Close to No. 6, but stem strongly pubescent: 

 leaves thick, very rough above, 3^ or less long : panicle branches more 

 numerous. — Dry woods from Courtney to Sibley. 



8. S. serotina Ait. l5°-6° high, glabrous : leaves lanceolate, thin- 

 nish, sharply serrate, rough-margined, smooth or slightly pubescent be- 



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