prickly ash, name for two deciduous shrubs or small trees (Zanthoxylum americanum and Z. clava-herculis) of the family Rutaceae (rue family). They are native to E North America and have prickly twigs and foliage similar to that of the unrelated ash tree. A pungent aromatic principle in the bark has been used as a home remedy for various ailments including rheumatism and toothaches (hence the local name toothache tree). Z. clava-herculis, of more southerly distribution, is also known as Hercules'-club. Both Hercules'-club and prickly ash are names sometimes used for an unrelated plant of the family Araliaceae (ginseng family). Other Zanthoxylum species are the sources of Sichuan and Sansho peppercorns (Z. simulans and Z. piperitum, respectively) and of satinwood (Z. flavum). Prickly ash of the genus Zanthoxylum is classified in the division Magnoliophyta, class Magnoliopsida, order Sapindales, family Rutaceae. The family Araliaceae belongs to the order Apiales.