Culture
Winter hardy to USDA Zones 2-10 where it is best grown in rich, humusy, fertile, consistently moist but well-drained soils in full sun to part shade. Generally intolerant of urban pollutants.
Noteworthy Characteristics
Populus nigra, commonly called black popular, is a large deciduous tree with a wide rounded crown that typically matures to 60-100’ tall. It is primarily native to boggy lowland areas, river valleys, pond margins, forest margins, fields and roadsides in Europe, northwestern Africa and western Asia. Dark gray bark on mature trees is knotted, deeply fissured, gnarled and burred. Alternate, simple, broadly triangular to diamond-shaped, deep green leaves (to 3” long) turn yellow in fall. Black poplar trees are dioecious (male and female flowers on separate trees). Catkins appear in late winter to early spring (March-April) before the leaves develop. Drooping male catkins (to 1-2” long) feature apetalous flowers with deep red anthers. More upright female catkins (to 4-5” long) feature apetalous flowers with two green stigmas. Pollinated catkins on female trees bear abundant masses of seeds by late summer, each seed being encased in white cottony hairs (sometimes commonly called seed wool or seed fluff) which facilitate wind-blown distribution of the seeds. To some, the cottony seeds exemplify the beauty of nature, but to others they amount to nothing more than landscape litter.
Some nurseries sell only male trees because many homeowners find the cottony seeds to be a somewhat untidy nuisance. On the other hand, a downside of male trees is that they produce abundant amounts of pollen which can adversely affect some allergy sufferers. Both sexes are guilty of dropping lots of leaves and twigs which require frequent clean-up. Roots may form suckers and can sometimes be invasive. Shallow spreading roots can lift pavements (sidewalks and streets), make lawn mowing difficult, damage septic tanks and drainage systems, and disturb prized garden areas.
Genus name comes from the Latin name.
Specific epithet means black.
Problems
Suseptible to a number of pests and diseases. Cankers are significant problems, especially in hot and humid climates. Cytospora canker attacks the upper branches of the tree and trunk and is often fatal. Additional potential disease problems include dieback, leaf spots, rusts and powdery mildew. Potential insect problems include aphids, borers, caterpillars and scale. Weak wood is easily damaged by wind. Shallow roots can lift sidewalks, make lawn mowing difficult, and damage drainage systems. Falling debris (leaves and twigs) requires frequent clean-up. Also avoid planting this tree in lawns or gardens. In Manual of Woody Landscape Plants, Michael Dirr sums up poplar pest problems by saying "if anyone plants poplars they deserve the disasters which automatically ensue."
Uses
Not considered to be a good landscape tree. Best used for windbreaks or screens or along roads.