252 American Midland Naturalist Monograph No. 7 



brous; stem slender, 15-60 cm 

 tall; heads few; involucre 5-7 

 mm high, the bracts acute, slen- 

 der, glabrous; rays 20-50, white 

 to pale lavender, 7-15 mm long; 

 wet ground and in bogs, rare, 



n.e. 111. Aug.-Sept 



A. junciformis Rydb. 



31. Leaves wider, mostly 1-3.5 cm wide 

 (except A. praealtus, with stout 

 stems 0.5-1.5 m tall, and numer- 

 ous heads) . 



32. Stem-leaves soft, flat, thin, dark 

 green, widest near the middle, 

 tapering toward each end, 

 mostly 1-3.5 cm broad; rays 

 usually white. 

 33. Leaves finely and softly 

 short-pubescent over the 

 lower surface; rays 15-25; 

 roadsides, fields, river 

 banks, common through- 

 out 111. Sept. -Oct 



A. ontarionis Wieg. 



33. Leaves glabrous or nearly 

 so, or pubescent only on 

 the midrib beneath. 

 34. Leaves with midrib on 

 lower surface usually 

 short-pilose pubescent; 

 heads tending to be uni- 

 laterally racemose ; in- 

 volucral bracts firm, lin- 

 ear-oblong, blunt or 

 acute, with conspicuous 

 subspatulate green tips: 

 rays 9-15, each 4-7 mm 

 long; woods, common. 



Sept. -Oct 



....A. lateriflorus (L.) Britt. 

 34. Leaves glabrous; panicle 

 large, with forking 

 branches; involucral 

 bracts narrowly linear, 

 attenuate, with a 

 green median band; 

 rays 20-40, each 6-12 

 mm long; moist 



