Nuttallia sinuata or Mentzelia sinuata
(Leachleaf Blazingstar)
Loasaceae (Loasa)
Mentzelia sinuata is found only along the foothills of the northern Front Range, primarily on shale outcrops. The bright yellow flowers open in the evening, so plants are usually seen with closed flowers. Plants grow to a height of 8 to 30 inches. Look for it on roadcuts on the east side of Horsetooth Reservoir.

Mentzelia sinuata is very similar to Mentzelia multiflora (not pictured). M multiflora has lighter colored flowers. For positive identification, the species are separated by looking at the texture of the seed coat under magnification.

Vegetation zone:  Foothills
Time of bloom:  July - September
Origin:  Native
Eastern Colorado Wildflowers