Populus heterophylla aka Swamp Poplar

Populus heterophylla is a deciduous tree in the willow family. Common names include swamp cottonwood, downy poplar, and swamp poplar. Its native range runs from eastern Canada to the southeastern United States. It grows beside rivers and in low, wet ground. Swamp edges and wet bottomlands form part of its habitat. It is not native to Britain or Ireland.

This large tree can reach 70–90 feet (21–27 metres). Its trunk can span 2–3 feet (0.6–0.9 metres) across. NC State notes that its shape is often poor. Virginia Tech describes a straight trunk with a clear lower section. The bark has deep ridges that run up the trunk. Bark shades range from brown to gray. Stout twigs are reddish brown or greenish brown, with pale lenticels. The pointed, reddish brown buds feel slightly sticky.

The simple leaves grow in an alternate pattern along branches. Each broad, egg-shaped leaf has a heart-shaped base. Leaves measure 4–7 inches long and have toothed edges. Their upper sides are green, with paler lower sides. Leaf stalks are round, and foliage can turn yellow. Male and female flowers grow on separate trees. Male catkins measure about one inch long. Female catkins bear sparse white flowers. Green, egg-shaped capsules grow in clusters and turn brown when ripe. They hold tiny seeds with a downy coat. Wind carries these seeds, which need moist sand to sprout.

Grow swamp cottonwood in full sun with ample root space. NC State lists moist soil and frequent standing water. Its suggested sites include ponds, river margins, and rain gardens. PFAF also reports growth in heavy, cold, damp soil. It favors deep, rich soil near neutral pH, with good drainage. Yet growth can slow in wet or poor acidic soils. Thin, dry soils also limit growth. It dislikes shade, crowded roots, and exposed upland sites. PFAF reports that it does not thrive in Britain.

NC State rates growth as medium; PFAF describes fast growth in the wild. Both sources describe a short-lived tree. Rabbits, deer, and livestock browse seedlings and young trees. Its soft, light wood serves for crates, baskets, and paper pulp. PFAF also lists boxes and indoor woodwork among its uses. Food evidence conflicts: NC State labels the fruit edible. PFAF records no known edible uses or hazards. Those entries do not establish safe use as food.