ves not petioled; stem-leaves with heart-shape clasping
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 divaricatus.=

225a. Stem-leaves clasping the stem by a cordate base
=Aster, Aster undulatus.=

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 cordifolius.=

230a. Heads few, seldom more than 10, in a loose spreading cluster
=Aster, Aster lindleyanus.=

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.

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 novae-angliae.=

235b. Involucre slightly glandular or not at all; rays 20-30, generally
blue-purple; leaves ovate-oblong =Aster, Aster patens.=

236a. Leaves o