Northern Prairie Wildlife Research Center
A true denizen of the plains and prairies, white-stemmed evening primrose is restricted to the belt of grasslands that extend from Alberta and British Columbia to Nebraska and Colorado. Plants of this species have been found in nearly every county in North Dakota.
The beautiful four-petaled white flowers of white-stemmed evening primrose are over an inch wide, with prominent yellow reproductive organs. Leaves are long and narrow. This is a bushy perennial that may reach a height of over three feet. The stems and branches are covered with a bark that looks like hard white enamel paint. This striking feature is found on few other plants.
White-stemmed evening primrose may be found in the dry prairie hills, especially those that are somewhat sandy or gravelly and have patches of exposed soil. Some Oenotheras are cultivated for the edible roots, but I found no mention of white-stemmed evening primrose in this regard.
Flowers of the evening-primrose family (Onagraceae) generally open in the late afternoon or evening for pollination by night-flying insects. Onagra and the generic name Oenothera stem from a name used by Theophrastus for the fireweeds that are also members of this family. Botanist Robert Sweet described white-stemmed evening primrose for science in 1830, dedicating the specific name to the eminent botanist Thomas Nuttall (1786-1859) who discovered the plant. Nuttall visited the Mandan villages in what now is North Dakota in 1811.