Populus deltoides is a tree to 30 m tall, to 100 cm dbh; roots shallow; vigorous, new long shoots angled, young bark smooth, yellow-green; old bark gray-brown, deeply ridged and furrowed, terminal winter buds to 2.5 cm long with 6-7 scales, very gummy
Leaves alternate, triangular (deltoid), coarsely toothed, tip pointed, base broadly truncate, those of short shoots 8-14 cm long, 8-14 cm wide, with 2-5 glands at base, leaves of long shoots variable, to 20 cm long, leaf stalk flat at top.
Flowers in catkins, blooms before leaves expand, sexes on separate plants (dioecious); males flower first, catkins about 10 cm long, reddish, female catkins about 22 cm, wind pollinated, March-April.
Fruit dry, an egg-shaped 0.6-1 cm long, seeds tufted, wind dispersed to about 100 m, or carried by water, May-June; germinate soon after falling. New seedlings require high moisture and full sun. Buds and catkins eaten by some birds (Martin et al. 1951).
Wetland status: FAC.
Frequency in New York City: Common.
Habitat: Open, moist fill and disturbed areas and flood plains. Tolerates salt and pollutants. Very intolerant of shade. Needs more than 1% full sun to grow (compensation point) can use up to 75% full sun to photosynthesize (saturation point) (Hicks and Chabot 1985). Moderately flood tolerant. Soil pH 4.6-6.5 (USDA, NRCS 2010) Found in soil pH 7.6 (Gargiullo unpublished data). Seeds eaten by numerous birds and small mammals (Martin et al. 1951).
Notes: Fast growing, short-lived woody pioneer. Stump sprouts if cut. Susceptible to fire damage. Attacked by numerous insects and fungi. Marssonina brunnea (Deuteromycotina, Coelomycetes) causes brown leaf spotting and defoliation. Wounded trees may become infected by a wood rotting fungus Ganoderma applanatum (Fomes applanatus; Basidiomycotina, Hymenomycetes). The fruiting body (Basidiocarp) is a large perennial, woody polypore bracket fungus to 50 cm wide and 5 cm thick, that has a white undersurface and margin with a reddish-brown top (“Artists conk”). The appearance of this fruiting body indicates serious rot has already occurred (Lincoff 1981). Trees weakened by drought, rapid freezing and warming or other stresses can be infected by Cytospora chrysosperma, (Deuteromycotina) a canker that kills branches or trunks. This is the asexual reproductive (conidial) state of the fungus Valsa sordida, (the sexual state of the fungus). The canker first appears as a brown, sunken patch on smooth bark or only as “spore horns” on old, fissured bark. These are masses of spores produced by reproductive bodies just below the bark. The spore mass is yellow, thread-like and coiled as it extrudes from the small bark lesions. Cottonwood leaves can be killed by the rust, Melampsora medusae, (Basidiomycotina). The spore masses of this fungus appear as yellow dots and patches on leaves in spring. An infection covering half the leaf will kill it. Another leaf pathogen of eastern cotton wood is Marssonina brunnea (Deuteromycotina, Coelomycetes), a leaf spot that is prevalent during wet weather. It appears as small, brown dots (ca 0.1 cm) on leaves soon after they expand in spring. A heavy infection causes leaf drop. Poplar mosaic virus (PMV) causes yellow spots and deformation of leaves. Eastern cottonwood may be defoliated by larvae of Hyphantria cunea, the fall webworm (Lepidoptera, Arctiidae). These caterpillars build a large, messy web around a branch. They are yellowish, hairy, with two rows of prominent black spots down their backs. Other Lepidopteran larvae that eat poplars include; mourning cloak butterfly (Nymphalis antiopa, Nymphalidae), dreamy dusky wing butterfly (Erynnis icelus, Hesperiidae), cecropia moth (Hyalophora cecropia Lasiocampidae), io moth (Automeris io, Saturniidae), big poplar sphinx moth (Pachysphinx modesta, Sphingidae), laurel sphinx (Sphinx kalmiae, Sphingidae), white-marked tussock moth (Orgyia leucostigma, Lymantriidae), black-etched prominent (Cerura scitiscripta, Notodontidae); (Pyle 1981; Covell 1984; Tallamy 2003).The larva of the cottonwood leaf beetle, Chrysomela scripta, (Coleoptera, Chrysomelidae), skeletonizes leaves. The adult is about 1 cm long, dull yellowish with black dots and stripes and usually found under cottonwoods. The larvae of Saperda calcarata (Coleoptera, Cerambycidae) the poplar borer tunnel through wood, making trees
susceptible to wind damage by weakening trunks, allowing entry other of borers and fungal pathogens. The adult is a dull, gray long horned beetle to 3 cm long. Both adults and larvae of Plectrodera scalator (Coleoptera, Cerambycidae), the cottonwood borer cause damage. The larvae bore holes into wood of the root crown weakening the trunk. The adults are black and white checkered long horned beetles to 3 cm long. They eat leaf stalks and bark of new shoots. Blackened, hanging shoot tips are a sign of this insect. Another wood borer is Cryptorhynchus lapathi, (Coleoptera, Curculionidae) the poplar-and-willow borer, a European hidden snout weevil, now well established here. The adults feed on green bark, but do little damage. Larvae feed on the inner bark of larger stems and tunnel up through trunks which may kill small trees (Burns and Honkala 1990; Sinclair et al. 1987; Johnson and Lyon 1991; White 1983; Covell 1984). A host tree of the Asian longhorn beetle, Anoplophora glabripennis (see Norway maple).