The leaves are oval, 3.7–16.7 cm (1+1⁄2–6+5⁄8 in) long and 2.5–13 cm (1–5+1⁄8 in) broad, oblique at the base, acute or rounded at the apex, with a wavy-toothed or shallowly lobed margin, and a short, stout petiole 6–15 mm (0.24–0.59 in) long; the midrib is more or less hairy, stout, with six to seven pairs of primary veins.

The young leaves open involute, covered with stellate rusty down; when full grown, they are dark green above, and paler beneath.

The fruit is a hard woody capsule 10–14 mm (0.39–0.55 in) long, which splits explosively at the apex at maturity one year after pollination, ejecting the two shiny black seeds up to 10 m (33 ft) distant from the parent plant.

[2][7] The pollinated ovary, protected by a persistent calyx, enters a resting state during the winter months.

[14] Early Puritan settlers in New England adopted this remedy from the natives, and its use became widely established in the United States.

The wood is light reddish brown, sapwood nearly white; heavy, hard, close-grained, with a density of 0.68.