930 COMPOSITAE Aster 



rowed at the base and more or less petiolate in nos. 12 and 27 and rarely a 

 few leaves petiolate in other species. 

 B. Stem leaves with their bases more or less cordate and clasping. 

 C. Involucral bracts and sometimes the peduncles glandular. 



Bracts narrowly linear, long-attenuate at the apex, mostly 6-9 mm long, 

 more or less suffused with purple; achenes about 1.5 mm long; 



plants of moist soil 9. A. novae-angliae. 



Bracts oblong-linear, merely acute at the apex or some of the inner 

 ones with acuminate tips, without purple color, mostly 4-6 mm long; 

 achenes about 2 mm long; plants of very dry habitats. 

 Stem leaves mostly 15-25 mm wide, the basal lobes developed so that 



the leaves appear perfoliate 10. A. patens. 



Stem leaves mostly 5-10 mm wide, their bases merely clasping. 



Pubescence of stem and branches dense, widely spreading 



11. A. oblongifolius. 



Pubescence of stem and branches not dense, upwardly appressed 



11a. A. oblongifolius var. rigidulus. 



C. Involucral bracts and peduncles not glandular. 



D. Stems entirely glabrous or sometimes pubescent in lines on the upper 

 part or in the inflorescence. 

 E. Leaves more or less serrate. 



Blades abruptly narrowed below the middle so as to form a 



broad-margined, entire petiole 12. A. prenanthoides. 



Blades not as above. 



Leaves gradually narrowed to a narrow base, rarely clasping; 

 heads mostly 15-20 mm wide; involucre 4.5-5.5 mm long. 



18a. A. paniculatus var. simplex. 



Leaves gradually narrowed to a wide clasping base; heads 

 large, mostly more than 20 mm wide; involucre 6 mm 



long or more 15. A. lucidulus. 



E. Leaves entire or some with a few short teeth near the middle. 

 Tips of the bracts squarrose or recurved-spreading. (See ex- 

 cluded species no. 631, p. 1098) A. novi-belgii. 



Tips of the bracts not squarrose or spreading. 

 Plants glaucous, glabrous or with a few lines of hairs on the 

 upper parts; leaves thick, very smooth, entirely glabrous 

 except the scabrous margins; the middle bracts short- 

 acute, with indurated tips, the green area short-rhom- 



boidal 13. A. laevis. 



Plants not as above. 



Bracts of nearly equal length, mostly 6-8 mm long. 



Leaves thin, usually less than 18 mm wide; branches 



generally longer than the subtending leaves; heads 



few or solitary at the ends of the branches; bracts 



in 1 or rarely 2 rows; lower part of stem generally 



2-3 mm in diameter 14. A. longifolius. 



Leaves thick, generally 15-30 mm wide; branches mostly 

 shorter than the subtending leaves; heads usually 

 several and somewhat in clusters towards the ends 

 of the branches; bracts in 2 rows; lower part of stem 



more than 4 mm in diameter 15. A. lucidulus. 



Bracts imbricated in 3-5 rows, of several lengths. 



Veinlets of under surface of blades conspicuous, the 

 areas enclosed by them about as long as wide; tall 

 plants with reddish brown stems; branches and 

 branchlets very leafy; leaves a yellowish green, 



