Populus L.

Leaves broad-elliptic, ovate, triangular or rhombic; usually more than 5 cm wide. Flowers with disc shaped nectary Populus
Leaves 3–9 cm long densely hairy below, 3–5-lobed or coarsely toothed. Catkins 3.5–6 cm long. Capsule c. 3 mm long. Spreading by suckers. Introd. from Eurasia and N. Africa Populus alba
Leaves 4–8 cm long, glabrous, closely toothed. Catkins 5–7 cm long. Capsule not seen. Spreading from suckers. Introd. from Eurasia Populus nigra