Disk flowers yellow.
147. Camphor weed. Heterotheca latifolia
151. Ciliate goldenweed. Haplopappus ciliatus
152. Maximilian sunflower. Helianthus maximilianii

Disk flowers not yellow.

153. Rose-ring gaillardia, Indian blanket flower. Gaillardia pulchella
154. Black sampson echinacea. Echinacea angustifolia
155. Prairie sunflower. Helianthus petiolaris
156. Common sunflower. Helianthus annuus

Leaves less than than 1/2 in. wide.

Many stem leaves.
158. Baby white aster. Leucelene ericoides
159. Cutleaf ironplant. Haplopappus spinulosus
161. Golden aster. Chrysopsis villosa var. villosa
166. Heath aster. Aster ericoides

Few stem leaves or all leaves at the base of the plant.

169. Plains daisy. Erigeron modestus
170. Trailing fleabane. Erigeron flagellaris
172. Aster. Aster subulatus var. ligulatus

More than 12 ray flowers 1/8-1/4 in.long.

173. Yerba de tajo. Eclipta prostrata