Northern Prairie Wildlife Research Center
| Lead | Characteristic | Go To |
| 1 | Petals minute or absent, greenish when present; seeds without a coma. | Genus Ludwigia |
| 1 | Petals white, pinkish or rose-purple; seeds with or without a coma. | Lead 2 |
| 2 | Plants annual; seeds without a coma. | Genus Boisduvalia (B. glabella) |
| 2 | Plants perennial, often flowering the first year; seeds with a coma. | Genus Epilobium |