Zanthoxylum clava-herculis, the Hercules' Club (or Hercules-club), pepperwood, or Southern prickly ash, is a spiny tree or shrub native to the southeastern United States. It grows to 10–17 m tall and has distinctive spined thick, corky lumps 2–3 cm long on the bark. The leaves are glabrous and leathery, pinnately compound, 20–30 cm long with 7-19 leaflets, each leaflet 4–5 cm long. The flowers are dioecious, in panicles up to 20 cm long, each flower small, 6–8 mm diameter, with 3-5 white petals. The fruit is a two-valved capsule 6 mm diameter with a rough surface, and containing several small black seeds. The tree has also been called Z. macrophyllum. The genus name is sometimes spelled Xanthoxylum.