Medium-sized tree 10 - 20 m tall, trunk diameter 30 cm - 0.8 m Leaves: alternate, on 2 - 5 cm long, flattened leafstalks, dark green and shiny above, paler and shiny beneath, 5 - 7 cm long, as wide or longer, diamond-shaped to triangular with a straight or broadly wedge-shaped base and long-pointed tip, round-toothed, firm, and thick. In autumn the leaves turn yellow. Flowers: all male, in hairy-bracted catkins. Catkin about 8 cm long and narrow. Stamens eight to ten. Filaments white. Anthers purple. Fruit: absent (no female flowers). All trees are male clones. Propagation is by cuttings (in cultivation) or root sprouts. Bark: thin and smooth on young trees, becoming grayish brown, thick, and deeply furrowed. Twigs: slender, stout, yellowish brown, shiny, becoming gray. Leaf scars triangular with three bundle scars each. Buds: slender, reddish brown, 8.5 mm long or less, conical, slightly angled, shiny, sticky, with overlapping scales. Terminal bud to 9.5 mm long. Form: narrowly columnar with a straight, slender trunk and upright branches.
Similar species: The similar Populus balsamifera and P. heterophylla differ by having rounded, not flattened leafstalks. Populus alba differs by having hairy leaves and leafstalks. For comparison, the similar leaves of P. deltoides (also triangular) have conspicuously incurved teeth and are longer than wide.
Flowering: April to May, before the leaves
Habitat and ecology: Introduced from Eurasia. Populus nigra (sometimes referred to as P. nigra 'Italica') is an infertile clone, descended from a single freakish individual. Propagation is by cuttings (in cultivation) or root sprouts. It is commonly planted in moist soils. However, there appear to be some spontaneous populations, particularly on and near the beaches of Lake Michigan.
Occurence in the Chicago region: non-native
Notes: Commonly planted as a windbreak along property lines. Populus species as a whole are subject to many diseases and insect pests, such as canker and tent caterpillars, which often kill the tree or make it unattractive. These risks, in conjunction with a water-hungry root system, have made Populus species less desirable for landscape use.
Etymology: Populus is the Latin word for poplar. Nigra means black.
Tall tree with dull gray branches and dark, furrowed bark on older trunks; petioles distinctly flattened; winter buds resinous; lvs pubescent when young, finely toothed, the teeth to ca 1 mm deep, more spreading than in no. 9 [Populus deltoides Marshall], only slightly or not at all incurved; lvs of short shoots rhomboid-ovate, with cuneate base, of long shoots broadly deltoid-ovate, truncate at base, abruptly pointed; floral disk 1-2 mm wide, stamens 20-30; stigmas 2, broadly dilated; frs ovoid, 7-9 mm, twice as long as the pedicels, with 4-8 seeds per placenta; 2n=38. Native of Eurasia, frequently planted, and occasionally escaped. The Lombardy poplar is a common horticultural form with erect branches, forming a long, columnar crown. (P. italica; P. nigra var. italica; P. dilatata)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.