Toothache tree, Zanthoxylum clava-herculis, is surely one of Arkansas’ most intriguing native plants.

Toothache tree
Photo by Sid Vogelpohl

If you haven’t been introduced, chew on a twig or a piece of bark for a few minutes and feel your mouth and tongue start to tickle and go numb.

(Please be sure that you have correctly identified the tree and you are not in fact chewing on a poison-ivy vine that might be climbing the trunk.)

Compound leaves of toothache tree
Photo by Sid Vogelpohl

Toothache tree (tickle tongue or prickly-ash or Hercules’ club) is covered with prickles from the compound leaves to the twigs and bark.

The conical to flattened bark projections are especially interesting, each with prominent layers of cork tipped with a sharp, delicate spine.

Toothache tree occurs in the southwestern half to two-thirds of the state on a variety of upland and poorly drained sites.

It blooms in the spring–pretty, but nothing spectacular. The species is a member of the citrus family, and like our wafer-ash (or hop tree) is a host for giant swallowtail butterfly larvae.

A second species, Z. americanum, is rare in northern Arkansas.

Sugarberry with similar bark architecture
Photo by Martha Bowden

The only other Arkansas trees with similar bark architecture are the sugarberries and hackberries, Celtis species, with amorphous, corky, wart-like protuberances.

Written by Eric Sundell

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