133 



234a. Involucre pubescent but not glandular 



Aster, Aster amethystinus. 

 234b. Involucre glandular Aster, Aster oblongifolius. 



235a. Involucre very glandular and viscid; rays very numerous, violet- 

 purple; leaves lanceolate Aster, Aster nOYae-angliae. 



235b. Involucre slightly glandular or not at all; rays 20 30, gen- 

 erally blue-purple; leaves ovate-oblong Aster, Aster patens. 



236a. Leaves of- a linear type 237. 



236b. Leaves broader than linear, at least 1 cm. wide 238. 



237a. Bracts narrow, approximately equal in length 253a. 



237b. Bracts of several lengths, the outer successively shorter 256a. 



238a. Leaves smooth above Aster, Aster laevis. 



238b. Leaves rough above 239. 



239a. Leaves contracted below the middle and then abruptly dilated to 

 the clasping base Aster, Aster prenanthoides. 



239b. Leaves gradually narrowed toward the base 



Aster, Aster puniceus- 

 240a. Rays conspicuous 241. 

 240b. Rays minute or wanting Aster, Aster angnstus. 



241a. Stems and leaves gray with a silky pubescence 



Aster, Aster sericeus. 



241b. Stem and leaves green, not silky 242. 



242a. Bracts glandular-viscid; rays violet 



Aster, Aster oblongifolius. 



242b. Bracts bristly-ciliate 243. 



242c. Bracts smooth or pubescent, not glandular or bristly- 

 ciliate 244. 



243a. Leaves crowded, rigid; rays white Aster, Aster nmltiflorus. 

 243b. Leaves not crowded and rigid; rays blue 234a. 



244a. Bracts narrowed at the tip into thickened firm green awl- 

 shape points 245. 

 244b. Bracts acute or obtuse at the flattened tip 247. 



245a. Involucre 4 5 mm. long 246. 



245b. Involucre 7 8 mm. high Aster, Aster polyphyllus. 



246a. Stem smooth Aster, Aster ericoides. 



246b. Stem hairy; leaves linear 



Aster, Aster ericoides var. yillosus. 

 246c. Stem densely white-woolly 



Aster, Aster ericoides Tar. platyphyllus. 



247a. Leaves at most 4.5 cm. long 248. 



247b. Leaves larger, at least the principal ones 249. 



