Hercules Club vs. Devil’s-Walkingstick

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Hercules club and devil’s-walkingstick both have ominous-sounding names and spiny stems; both are native to the Eastern NC area; and their common names are sometimes used interchangeably. Throw in the name “toothache tree” and the confusion can deepen. Let’s try and sort this out, because when you look closely at the actual plants, they’re quite easy to distinguish.

Of our two main protaganists, devil’s-walkingstick (Aralia spinosa) is far more common and widely distributed. It’s easy to spot alongside the edges of wetlands, along roadsides, edges of open parks, or your own backyard. You might find one plant, or a dense thicket. Hercules club (Zanthoxylum clava-herculis) is far more likely to be found in hot, sandy locations such as Carrot Island in Carteret County.

The stems of devil’s-walkingstick are dark-colored and slender with numerous sharp spines, as compared with the light gray bark and large, blocky-pyramidal spines of mature Hercules club stems. The foliage of devil’s-walkingstick has the unusual distinction of being bipinnately compound, as compared with the pinnately compound arrangement of Hercules club (see image of green ash foliage below for comparison). Another key difference in foliage characteristics is that Hercules club has some very prominent spines along the length of the rachis (the axis bearing the leaflets), whereas devil’s-walkingstick has scattered prickles along the petiole (leaf stalk) and rachis. The fruit of devil’s-walkingstick is borne in huge, showy clusters in late summer or fall; the smaller clusters of Hercules club fruit can be seen in May.

Image of aralia spinosa

Aralia spinosa

Image of zanthoxylum clava-herculis

Zanthoxylum clava-herculis

Image of a single, compound pinnate leaf of green ash (Fraxinus pennsylvanica)

A single, compound pinnate leaf of green ash (Fraxinus pennsylvanica)

Image of compound pinnate foliage

Compound pinnate foliage of Zanthoxylum clava-herculis, with thorns.

Image of aralia spinosa

Aralia spinosa; not a leaf.

Image of a non-leaf

Still not a leaf

Image of large spinosa leaves

Now that’s a leaf … 36” long and 37” wide at the widest point. A. spinosa leaves can grow up to five feet long.

Image of a terminal fruit cluster of Zanthoxylum clava-herculis

Terminal fruit cluster of Zanthoxylum clava-herculis, Carrot Island, NC.

How does the “toothache tree” fit into the story? Toothache tree is a common name sometimes used for Zanthoxylum clava-herculis, because oil from the bark has medicinal qualities, and historically the bark has served as a home remedy for toothaches and other ailments. For the same reason, this common name is also used for the closely related Zanthoxylum americanum. However, Z. americanum is rare in the Carolinas (apparently a small distribution exists in South Carolina), and occurs primarily in the Northeast and Midwest regions of the U.S. A major distinguishing characteristic between the two species is that the fruit of Z. americanum is produced in clusters along the stems, while the fruit of Z. clava-herculis is produced at the ends of stems.

“Toothache tree” is not the only common name that gets thrown around a bit loosely. A. spinosa is sometimes called Hercules-club. Prickly-ash may be used to describe Z. clava-herculis, Z. americanum, and even A. spinosa.

It’s tempting to say that the “proper” common name for A. spinosa should be devil’s walking-stick; for Z. clava-herculis, Hercules-club; and for Z. americanum, toothache tree. But that’s not the way common names work, so to get around potential confusion it’s best to just focus on the botanical or scientific names. That’s where true botanical authority and consistency can be found.