Evening Primrose (Oenothera biennis), 620 Certified Pure Live Seed, True Native Seed FREE SHIPPING Number of seed is Pure Live Seed, not bulk Species is US Native, not introduced alien We grow the seed so we control quality A 3 to 6 tall native biennial with a terminal spike producing 1  wide yellow flowers. A summer and fall night flowering plant preferring dry to medium soils in full sun or part shade.