Northern Prairie Wildlife Research Center
| Lead | Characteristic | Go To |
| 1 | Large tree; leaf blades deltoid-ovate; flowers subtended by an obliquely cup-shaped disk; catkin bracts fimbriate; stamens (30)40-80; capsules 3- or 4-valved. | Genus Populus |
| 1 | Shrubs and trees; leaf blades ovate, elliptic, lanceolate, linear-lanceolate, obovate or oblanceolate; flowers subtended by 1 or 2 enlarged glands; catkin bracts entire; stamens 2 or 3-8(12); capsules 2-valved. | Genus Salix |