Northern Prairie Wildlife Research Center
| Lead | Characteristic | Go To |
| 1 | Petals elliptic, broadest near the middle, tapered to a subacute tip; flowers usually fragrant; rhizome lacking tubers. | N. odorata |
| 1 | Petals oblanceolate to spatulate, broadest above the middle, obtuse to rounded at the tip; flowers scarely if at all fragrant; rhizome with lateral tubers. | N. tuberosa |