Oenothera parviflora L.
Family: Onagraceae
northern evening-primrose, small-flowered evening-primrose
Oenothera parviflora image
Merel R. Black  
Etymology: Oenothera: from Greek oinos, "wine," and thera, "to imbibe," because an allied European plant was thought to induce a taste for wine
Plants: erect, biennial, 2'-6' tall forb, mostly hairless or only finely fuzzy
Leaves: lance-like to oblong, alternate
Flowers: yellow, 4-parted, 3/4"-1 1/2" wide; inflorescence a terminal, usually unbranched spike nodding at the tip
Fruits: capsule slightly tapering towards top; seeds without tufts of hair at the top
Habitat: disturbed sites