Prickly ash (Zanthoxylum parvum), currently blooming in the Woodland Garden, is an aromatic, spiny, thicket-forming deciduous shrub or small tree that, as the common name suggests, resembles (particularly in leaf) an ash with prickles. But somewhat surprisingly, it’s not an ash at all, but a member of the citrus family (Rutaceae). First described in Philip Miller’s Gardener’s Dictionary (1768), it was noted to be “grow[ing] naturally in Pensylvania [sic] and Maryland”. Another apt common name for prickly ash is ‘toothache tree’, because indigenous Americans chewed the bark or fruits, which produced a numbing effect for relief from toothache pain.
All parts of this small native tree have a bright, lemony fragrance. In the landscape, it is most useful for hedgerows, screens, or naturalized woodland areas. “Butterfly Bob” Snetsinger chose to plant prickly ash at the SBG to attract giant swallowtail and tiger swallowtail butterflies, for whom it is a host plant. Its flowers are greenish-yellow, inconspicuous but fragrant, and are quite attractive to bees. Female flowers give way to clusters of reddish-brown, berry-like fruits (follicles) which mature in late summer and are eaten by many birds and small mammals.
Need some lemony-fresh flavor for your landscape? Try prickly ash!
