Erysimum asperum (Prairie Rocket)
Family:
Brassicaceae (Mustard)
  
Erysimum asperum is very similar to Erysimum capitatum. E. asperum is found on the plains, but it's range continues to higher elevation and overlaps with the range of E. capitatum. Weber describes E. asperum as having gray-pubescent seed pods, compared to greener, smoother seed pods on E. capitatum.

Vegetation zone:  Plains, Foothills, Montane
Time of bloom:  April - August
Origin:  Native
Eastern Colorado Wildflowers