Deciduous trees to 40m high with smooth grey or white bark, sometimes rough on the lower trunk. Leaves usually roughly triangular or diamond-shaped, on a long stalk, with a paler green or white underside. Tiny flowers in long drooping catkins are produced in spring and may be followed by tiny seeds with a fluffy parachute of hairs which are released in late spring.

Usually in damp soils or in river beds. Sometimes planted to stabilise river banks, but they may in fact cause erosion by creating dense thickets which divert flows against the opposite bank and may spread downstream away from the planting site.

The main form of spread is by root suckers around the parent plant, forming large thickets. White or silver poplar (Populus alba) and Lombardy poplar (Populus nigra var. Italica) sucker the most. Spread over greater distances occurs when dumped material or branches detached in floods take root.

Some poplars can produce copious seed crops, particularly white poplar, but seed may not be viable as seedlings seldom or never result.

There has been some indication that different species of poplar can hybridise like the willows and produce fertile offspring from seed. Cottonwood (Populus deltoides) and Lombardy poplar are the species which have been implicated to date, but the potential is there for other species to hybridise if planted within a suitable distance of each other. At this point it appears that not all poplars are invasive but given this potential for hybridisation it would be safer to avoid planting them. In general it is best to plant natives for river bank stabilisation.

There are no similar natives. White poplar can be confused with the exotic birches (Betula species) some of which also have very white bark, but birches do not have the white leaf underside and do not sucker. The willows are similar, particularly pussy willows which have broad leaves, but their leaves are not triangular or diamond shaped.

Cut and paint, stem inject or spray smaller plants. Treat plants when in full leaf, in summer or early autumn. Some poplars will sucker massively if cut and repeated cut and paint will be needed.