Thistle Family. 79 



margins. Receptacle convex, punctate. Pappus of minutj bristles and often 

 2-3 awns. Achenes flat, obovate, 3-3-winged. 



B. asteroides (L.) L'Her. Stem 1-0 feet high; leaves long-lanceolate, en- 

 tire; involucral scales acuminate. Moist soil, sloughs and low places; July- 

 September; frequent; Muscatine, Johnson, Henry, Lee, Decatur, Ringgold, 

 Taylor, Winnebago, and Emmet counties; reported from Story, Harrison, Mo- 

 nona, and Woodbury counties. 



ASTER L. Asl'kk. Perennials, with alternate leaves, and panicled, cor- 

 yinbed, or racemose heads. Disk-flowers perfect, yellow to purplish; rays 

 pistillate, 3-toothed at the apex; white, blue, or purple, never yellow. In- 

 volucral scales loose, imbricated, often with green tips. Pappus simple, or 

 double in the last, capillary. Receptacle flat, alveolate. Achenes compressed. 

 Common in late summer and autumn. 



A. Pappus simple, nf capillary bristles. 



* Liwzr anilh is.il leaves cord tie aad sleudsr-pelioled, the stem leave? not cordate- 



claspinq. 

 f Rays while, violet, or ri.se. 



A. corymbosus Ait. Stem 1-2 feet high, nearly smooth, somewhat flex- 

 uous: leaves ample, ovate, acuminate, thin, coarsely serrate, all but the up- 

 permost with a heart-shaped base, and on long wingless petioles; heads ob- 

 lojir, in small open corymbs; rays ii-9, white. Rich woods; Muscatine county. 

 ( A. divaricatas \i. ) 



A. macrophyllus L. Stem 2-3 feet high, rigid, rough-pubescent: leaves 

 thickish, rough, serrate, pubescent beneath, the upper ovate or oblong, ses- 

 sile or on margined petioles, the lower cordate and long-petioled; heads one- 

 half inch high, larger than the preceding; scales obtuse, the inner longer and 

 thinner. Hilly woodlands, not rare; Muscatine county. 

 \ f Rays blue or purple, rarely wltile. 

 \ Leaves entire or nearly so, fi,rm, or thick. 



A. azureus Lindl. Stem 1-3 feet high, rigid, roughish, paniculutely 

 branched; leaves rough, the radical and lower cauline leaves lanceolate, more 

 or less with cordate bases, on long petioles, the upper lanceolate to linear or 

 subulate, wing-petioled or with attenuated base to sessile; rays violet blue; 

 involucre obconic; scales with abrupt green tips, appressed. Prairies and 

 thickets; frequent; Johnson, Story, Des Moines, Appanoose, and Decatur 

 counties. 



A. shortii Hook. Stein 2-4 feet high, rough-pubescent; leaves lanceolate 

 or ovate-lanceolate, long-acuminate, entire, on slender naked petioles, base 

 deeply cordate, smooth above, minutely pubescent beneath, the upper leaves 

 sessile; racemes paniculate; involucre campanulate; scales with green tips. 

 Cliffs and banks; infrequent; Winneshiek, Muscatine, Johnson, and Lee coun- 

 ties, reported from Fayette county. 



| f Leaves rn/istly sluirply serrate. Villi. 



A. cordifolius L. Stem 1-3 feet high, smooth or slightly pubescent, rarely 

 hairy, panicuhitely branched above; leaves ovate-cordate, sharply serrate, on 

 lono- slightly margined petioles, or upper lanceolate and sessile; heads pan- 

 icled- rays pale blue or white; iuvolucre obconic, scales appressed, tipped with 

 short green points. Woods; common; Winneshiek, Johnson, and Decatur 

 counties, reported from Fayette, Story, and Des Moines counties. 



A. saqittifolius Willd. Stem 2-4 feet high, rigid; leaves ovate-lanceolate, 

 pointed, serrate, pubescent beneath, the lower with the base truncate or cor- 



