Calylophus serrulatus
(Yellow Sundrops)
Onagraceae (Evening Primrose)
Yellow Sundrops can grow to a height of 2 to 3 feet. Leaves have small teeth on the margins. It is found on dry sites on the plains of eastern Colorado.

Compare to Calylophus lavandulifolius, which is a smaller plant with narrower leaves that lack teeth.

Vegetation zone:  Plains
Time of bloom:  May - July
Origin:  Native
Eastern Colorado Wildflowers