Prickly Ash, an aromatic shrub or small tree with spiny branches. It is not a true ash. There are about 200 species, native to North and South America, Africa, Asia, and Australia. The prickly ash has small, greenish flowers, which develop into fleshy, reddish pods, each containing a single black seed. The leaves resemble those of the ash.

The southern prickly ash, or Hercules' club, is native to the southeastern United States. (The name Hercules' club is shared by a similarly thorny but unrelated tree, which, in turn, is frequently called prickly ash.) The northern prickly ash, or toothache tree, grows in southern Canada and the eastern United States. The bark and leaves of both species are chewed as a folk remedy for toothache.

Prickly ash belongs to the rue family, Rutaceae. The southern prickly ash is Zanthoxylum clavaherculis; the northern, Z. americanum. The other tree known as Hercules' club is Aralia spinosa of the ginseng family, Araliaceae.