Oenothera glazioviana Micheli
Family: Onagraceae
garden evening-primrose, red-sepal evening-primrose
[Oenothera erythrosepala Borbas,  more...]
Oenothera glazioviana image
from USDA Plants website  
Etymology: Oenothera: from Greek oinos, "wine," and thera, "to imbibe," because an allied European plant was thought to induce a taste for wine
Plants: biennial/perennial forb
Conservation Status: Introduced - adventive