254 American Midland Naturalist Monograph No. 7 



shorter; achenes pubescent; moist ground in 

 the northern half of the state, local. Aug.-Oct. 

 [Docllingeria umbcllata (Mill.) Nees]. Flat-top 

 Aster A. umbellatus Mill. 



1. Heads rayless, campanulate, 8-12 mm broad; involucre 4-6 mm 

 high; pappus copious, soft; achenes appressed-pubescent; leaves 

 linear, entire, sessile, ciliolate, acutish; plants annual; road- 

 sides and waste ground, local; adv. from w. U.S.; apparently 

 not coll. recently in 111.; Cook Co., Moffatt in 1891; Hill in 

 1900, Agues Chase in 1900. July-Sept. [A. angustus sensu auth., 

 non Nees; Brachyactis angustus (Lindl.) Britt.] Rayless Aster. 

 A. brachyactis Blake 



20. Erigeron L. — Fleabane 



1 . Rays conspicuous, longer than the pappus. 



2. Leaves clasping; rays lilac or purple; plants perennial. 



3. Heads few, 2.5-3.5 cm in diameter; rays 50-75, about 1 mm 

 broad; peduncles hirsute; stem simple, rather leafless 



above; open woods, common. Apr.-June 



E. pulchellus Michx. 



3. Heads several, 1.5-2 cm in diameter; rays 150-200, about 



0.5 mm broad; peduncles strigose; stem branched, leafy; 

 open woods, roadsides, and fields, common. May-June 



E. philadelphicus L. 



2. Leaves not at all clasping; rays white or pink-tinged; plants 

 annual or biennial. 



4. Stem-leaves few, linear to narrowly lanceolate, strigose, usual- 



ly entire; stem softly strigose, 30-70 cm tall; basal leaves 

 spatulate; roadsides, fields, or dry open woods, chiefly in 

 the northern half of the state. May-July. Daily Fleabane 

 [E. ramosus (Walt.) BSP.] E. strigosus Muhl. 



4. Stem-leaves more numerous, lanceolate, ciliate, sparsely hir- 

 sute or glabrous, irregularly sharply toothed, or the upper 

 ones entire; stem 60-150 cm tall, scabrous to hispidulous; 

 basal leaves ovate, coarsely dentate, long-petioled, usually 

 absent at flowering time; fields, roadsides, waste places, and 

 open woods, very common throughout 111. June-Oct. 



Whitetop E. annuus (L.) Pers. 



I . Rays inconspicuous, scarcely, if at all, exceeding the pappus. 



5. Rays purplish; involucre about 2 mm high; stem diffusely or 

 divaricately branched; leaves all linear, entire; dry soil, local. 

 June-Sept E. divaricatus Michx. 



5. Rays white; involucre 3-4 mm high; stem strict; lower leaves 

 spatulate, toothed; common weed in cultivated ground and 



along roads. Aug.-Oct. Horseweed. Muletail 



E. canadensis L. 



