Ohio buckeye can be a shrub or a medium-sized tree, depending on site conditions, with branches drooping with upcurved ends.
Leaves are opposite, palm-shaped compound, with usually 7 leaflets; leaflets 4–6 inches long, 1½–2½ inches wide, broadest in the middle, margin finely toothed; upper surface bluish- or grass green; lower surface paler, smooth.
Bark is dark brown when young, smooth; older bark gray and broken into plates roughened by small, numerous scales, foul smelling.
Twigs are reddish brown to gray, hairy at first, smooth later; pores orange; leaf scars large.
Flowers April–May, greenish yellow, each flower about ¾ inch long, clustered along an axis 4–8 inches long at the tips of twigs; petals 4, stamens longer than the petals.
Fruits September–October, a light brown, leathery capsule; 1–2¼ inches across; globe-shaped, roughened by blunt spines, splitting into 3 parts; seeds 3, brown, shiny.
Similar species: Red buckeye (Aesculus pavia) is native to our extreme southeastern counties. It has red (not greenish-yellow) flowers with shorter stamens, has usually 5 (not 7) leaflets, and has fruits that lack spines.