Height up to 2 m. Plants feature large compound leaves and numerous (50 to 900), tiny white flowers clustered on branched bottlebrush-like flower spikes (racemes). The alternate leaves are divided into threes, with 9-17 lobed leaflets, each up to 18 cm long. The flowers of tall bugbane lack petals and instead attract pollinators with numerous showy white stamens. Each flower is surrounded by five tiny sepals. Unlike other members of the genus Actaea, fruits are green pod-like structures (up to 1 cm long) that remain on the plant long after flowering and split open in fall or winter to release about a dozen reddish-brown seeds.