194 COMPOSITAE 



neath : heads %"-Z" high : scales of involucre thin : rays 7-15. — Common 

 in low grounds along the Missouri River. July-September. 



9. S. Missotiriensis Nntt. l°-3° high, glabrous throughout : leaves 

 linear-lanceolate, thick, entire or strongly serrate : heads 2"-3" high : 

 scales of involucre thick : rays 6-13. — Not uncommon locally on dry 

 prairies throughout the southern part. July-September. 



10. S. Canadensis L. 3°-6° high, finely pubescent : leaves lanceo- 

 late, sharply serrate, roughish above, pubescent beneath : rays 9-15.— 

 Yery common in dry grounds throughout. August-September. 



Var. scabriuscula Porter. Leaves very rugose beneath, somewhat 

 shorter than the type. — Frequent along the Missouri River bluffs, espe- 

 cially around Courtney. 



Var. procera (Ait.) T. & G. Leaves cinereous pubescent, especially 

 beneath. — Common on a rocky hill near Pixleys. 



11. S. nemoralis Ait. l°-3° high, grayish-pubescent : leaves ob- 

 lanceolate to oblong-spatulate, crenate-toothed, more or less roughish, 

 and appressed grayish-pubescent : inflorescence usually not one-sided : 

 rays,7-10, less than V long. — Not uncommon in dry grounds, especially 

 in the southern part. Very variable. August-September. 



12. S. longipetlolata Mackenzie & Bush, u, sp. 10'-24' high, canes- 

 cent, green : lower leaves linear- obi anceolate, long petioled, short crenate 

 to entire, appressed-pubesoent on both sides : inflorescence strongly one- 

 sided : rays 3-10, over 1 J" long. — Frequent in dry ground throughout the 

 southwestern part. August-October. 



10. EUTHAMIA Nutt. 



Perennial herbs with linear to linear-lanceolate leaves. Heads numerous 

 in a flat-topped cyme. Involucie imbricated. Receptacle fimbrillate. Ray 

 flowers pistillate. Disk flowers peifeot. 



1. E. graminifolia (L.) Nutt. Goldbn Rod. 2°-4° high, nearly 

 glabrous : leaves 3-5-nerved : rays 12-20. — Frequent on prairies through- 

 out, especially in the southern part. August-September. 



11. BOLTONIA L'Her. 



Perennial herbs with alternate entire leaves. Involuoral bracts imbri- 

 cated. Receptacle naked. Ray flowers pistillate. Disk flowers perfect. 

 Achenes flat, with thickened margins. 



1. B. asteroidea (L.) L'Her. Swamp Astke. 4°-8° high, glabrous: 

 leaves lanceolate, sessile : flowers very numerous, white : involncral 

 bracts lanceolate to spatulate, obtuse to mucronate. — Abundant locally in 

 low grounds throughout the northern part. August-October. 



12. ASTER L. 



Perennial herbs with alternate leaves and corymbose or paniculate in- 

 florescences. Kay flowers pistillate. Disk flowers fertile. Receptacle 

 fiat. Achenes flattened. 



