254 American Midland Naturalist Monograph No. 2 



1 1 . Stem glabrous, or the upper part pubescent in lines. 

 15. Stem-leaves toothed; rays purple (rarely white). 



16. Leaves oblanceolate, acuminate, sharply serrate, abruptly con- 

 tracted into winged entire auriculate-clasping petioles; 

 moist ground, often along streams or ditches, Fulton, 



Peoria, and Henry counties. Sept. -Oct 



_../4. prenanthoides Muhl. 



16. Leaves lanceolate, toothed, sessile, those of the branches 

 smaller and entire; moist ground, n.e. 111., extending s.w. to 



Menard Co. Aug. -Oct A. lucidulus (Gray) Wieg. 



15. Leaves entire or nearly so, lanceolate or oblanceolate, glabrous 

 and glaucous, the margins scabrous; sandy soil in woods, usual- 

 ly near streams. Aug. -Oct. Smooth Aster A. laevis L. 



10. Leaves not clasping. 



17. Rays present, conspicuous; plants perennial. 



18. Leaves densely appressed silvery-silky on both sides; rays violet; 



sandy soil, often in open woods, local. Sept.-Oct 



_ A. sericeiis Vent. 



18. Leaves not silvery-silky. 



19. Heads not in flat-topped corymbs. 



20. Involucre conspicuously turbinate, 10-12 mm. high, the 

 bracts linear-spatulate, obtuse, appressed, rounded on 

 the back, imbricated in 5 or 6 series, their tips green 

 only at the apex; rays violet-blue; prairie soil, local; 

 chiefly in the s. part of the state, but extending northw. 



to Christian and Fulton counties. Sept.-Oct 



A. turbiriellus Lindl. 



20. Involucre hemispherical to campanulate; bracts not round- 

 ed on the back. 

 21. Involucres 3-7 mm. high. 



22. Bracts (at least the outer) bristly-ciliate, the tips 

 recurved; heads small, densely clustered. 

 23. Rays white. 



24. Stem with spreading or slightly reflexed 

 hairs; bracts (at least the outer) hispidu- 

 lous on the back; dry ground, prairie soil, 

 often along roads, common. Sept.-Oct. 

 [/I. multiflorus of auth., ex p. not Ait. 

 A. ericoides var. prostrates (Ktze) 



Blake] A. exiguus (Fern.) Rydb. 



24. Stem with appressed or ascending short 

 hairs, or the lower part glabrous; bracts 

 smooth or nearly so on the back; in habi- 

 tats similar to the preceding, but less 

 common; chiefly in the n. half of 111. 

 July-Oct. [A. 7ntdtiflorus Ait.; A. stricti- 

 caulis Rydb.] A. ericoides L. 



