Northern Prairie Wildlife Research Center
| Lead | Characteristic | Go To |
| 1 | Stems armed with nodal spines. | R. missouriense |
| 1 | Stems lacking spines. | Lead 2 |
| 2 | Leaves dotted beneath with shiny, yellow to brown, resinous glands. | R. americanum |
| 2 | Leaves without resinous glands. | R. triste |