Phlox divaricata (wild blue phlox)

Also called woodland phlox, this is an excellent phlox for shade. The fragrant pale violet to white flowers bloom for three or more weeks. Spreads slowly by rhizome. 

Tip: To distinguish this plant from the invasive dame's rocket, count the number of petals. Phlox has five letters and five petals. Dame has four letters and four petals.