Oenothera jamesii --River Primrose--

Erect, biennial with large fragrant, evening-blooming bright-yellow flowers in clusters - blossoms darken to orange as they close off. Grows up to 6' H and flowers in full summer to fall (July-October). Full sun, well-drained soil, though it does like more water than some natives - it tends to grow near streams. Attracts butterflies.