Populus L. >

Leaves broad-elliptic, ovate, triangular or rhombic; usually more than 5 cm wide. Flowers with disc shaped nectary Populus
consider the other alternative
Leaves 4–8 cm long, glabrous, closely toothed. Catkins 5–7 cm long. Capsule not seen. Spreading from suckers. Introd. from Eurasia Populus nigra