Nuttallia nuda or Mentzelia nuda
(Bractless Blazingstar)
Loasaceae (Loasa)
Flowers of Nuttallia nuda have ten non-overlapping petals and numerous long stamens. Flowers open in late afternoon. Nuttallia nuda is a common plant on dry, sandy plains sites.

Compare to Nuttallia decapetala.   N. decapetala has larger flowers with yellow stamens and petals that sometimes overlap. Leaves of N. decapetala are often more deeply lobed.

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