Genus 31.] 



THISTLE FAMILY. 



34. Aster laevis L,. Smooth Aster. 

 (Fig. 3768.) 

 Aster laevis L. Sp. PI. 876. 1753. 



vStem usually stout, glabrous, often glaucous, 

 2-4 high, branched or simple. Leaves thick, 

 entire, or serrate, glabrous, slightly rough-mar- 

 gined, the upper all sessile and strongly cor- 

 date-clasping, oblong-lanceolate, oblanceolate or 

 ovate, acute or obtusish, i / -4 / long, 4 // -2 / wide, 

 the basal and lower gradually narrowed into 

 winged petioles, those of the branches often 

 small and bract-like; heads usually numerous, 

 about 1' broad; involucre campanulate,its bracts 

 rigid, acute, appressed, green-tipped, imbricated 

 in several series; rays 15-30, blue or violet; pap- 

 pus tawny; achenes glabrous or nearly so. 



Usually in dry soil, Maine and Ontario to Penn- 

 sylvania and Louisiana, west to the Northwest Ter- 

 ritory and Missouri. Sept. -Oct. 

 Aster laevis amplifolius Porter, Mem. Torr. Club, 5: 

 324. 1894. 



Stout, somewhat fleshy; leaves broadly ovate, nar- 

 rowed toward the base, strongly clasping. Massa- 

 chusetts to eastern Pennsylvania, Minnesota and Missouri. 



Aster laevis Potomacensis Burgess. 

 Lower stem-leaves abruptly contracted into winged petioles, sharply serrate; heads few, usu- 

 ally racemose; green tips of the bracts broad, conspicuous. Maryland and Virginia. 



35. Aster concinnus Willd. Narrow- 

 leaved. Smooth Aster. (Fig. 3769.) 



Aster concinnus Willd. Enum. 884. 1809. 



Similar to narrow-leaved forms of Aster laevis, 

 glabrous, or sparingly pubescent above; stem 

 paniculately branched, i-3 high. Leaves 

 light green, lanceolate to linear, entire, or some- 

 times serrulate, the upper sessile, somewhat 

 clasping, i / -3 / long, the lower and basal ones 

 spatulate, or oblong, narrowed into margined 

 petioles, sometimes coarsely toothed; heads 

 usually numerous, about 1' broad; bracts of the 

 involucre with rhomboid acute herbaceous tips; 

 rays violet to purple. 



New York and Pennsylvania to Virginia, North 

 Carolina (?) and Arkansas. 



36. Aster purpuratus Nees. Southern 

 Smooth Aster. (Fig. 3770.) 



Aster virgatus Ell. Bot. S. C.& Ga. 2: 353. 1824. Not 



Moench, 1S02. 

 A. purpuratus Nees, Gen. & Sp. Ast. 118. 1832. 



Stem slender, glabrous, simple, or branched 

 above, i}4-3 high, the branches sometimes pu- 

 berulent. Leaves firm, glabrous, dark green, entire, 

 the upper sessile and clasping at the base, elon- 

 gated-lanceolate or linear-lanceolate, acuminate, 

 2 / -6 / long, 2 r/ -4 r/ wide, the lower and basal ones 

 petioled, oblong-lanceolate, obtusish, those of the 

 branches very small; heads rather few, loosely 

 paniculate, S // -I2 // broad; involucre campanulate, 

 to turbinate, its bracts coriaceous, linear, appressed, 

 green-tipped, acute, imbricated in several series, the 

 outer shorter; rays 5-10, blue or violet, 3 // ~5 // long, 

 pappus tawny; achenes glabrous. 

 , Virginia and West Virginia to Georgia and Texas. 



24 



Aug. -Sept. 



