Oenothera nuttallii
(Nuttall's Evening Primrose)
Family:
Onagraceae (Evening Primrose)
  
Oenothera nuttallii is a tall, white Evening Primrose. Leaves are narrow. Plants are 1 to 3 feet tall and grow on dry sites

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