132 



219a. Stem-leaves linear, entire Fleabane, Erigeron raniosus. 



219b. Stem-leaves ovate-lanceolate, the principal ones toothed 220. 



220a. Rays 100 or more, light-purple or pink 



Fleabane, Erigeron philadelphicus. 

 220b. Rays much fewer, white Fleabane, Erigeron annuus. 



221a. Basal leaves petioled and heart-shape at the base 222. 



221b. Basal leaves not petioled; stem-leaves with heart-shape clasp- 

 ing bases 231. 



221c. Basal and stem-leaves sessile or petioled, but never heart-shape 

 or clasping 240. 



222a. Rays white or violet 223. 

 222b. Rays blue 225. 



223a. Plant glandular, especially on the pedicels and branches of 

 the inflorescence Aster, Aster macrophyllus. 



223b. Plant not glandular 224. 



224a. Leaves rough above Aster, Aster schreberi. 



224b. Leaves smooth above Aster, Aster diyaricatus. 



225a. Stem-leaves clasping the stem by a cordate base 



Aster, Aster undulatns. 



225b. Stem-leaves not cordate-clasping 226. 



226a. Leaves entire 227. 

 226b. Leaves serrate 228. 



227a. Leaves glabrous above Aster, Aster shortii. 



227b. Leaves rough above Aster, Aster azureus. 



228a. Involucre 4 6 mm. long 229. 

 228b. Involucre 6 10 mm. long 230. 



229a. Leaves rough; petioles mostly winged 



Aster, Aster lowrieanus. 

 229b. Leaves smooth; petioles slender, not winged 



Aster, Aster cordifolins. 



230a. Heads few, seldom more than 10, in a loose spreading 

 cluster Aster, Aster lindleyanns. 



230b. Heads numerous, in a rather elongate crowded cluster 



Aster, Aster sagittifolius. 



231a. Stem hirsute or rough-pubescent 232. 

 231b. Stem smooth, or essentially so 236. 



232a. Leaves conspicuously serrate Aster, Aster puniceus. 



232b. Leaves entire or nearly so 233. 



233a. Leaves narrowed toward the base and barely clasping, linear 



or oblong-linear 234. 

 233b. Leaves ovate-oblong or lanceolate, with a broad conspicuously 



clasping base 235. 



