Description: English: Oenothera pilosella. Date: 18 March 2012. Source: http://plants.usda.gov/java/largeImage?imageID=oepi2_001_ahp.tif. Author: Robert H. Mohlenbrock. USDA SCS. 1989. Midwest wetland flora: Field office illustrated guide to plant species. Midwest National Technical Center, Lincoln. Courtesy of USDA NRCS Wetland Science Institute.