Tree of the Week: Toothache Tree (Zanthoxylum clava-herculis)

Today, we added a tree to the arboretum catalogue. Some time in the past few years, a toothache tree (Zanthoxylum clava-herculis) volunteered in a dewberry bed on the west side of Mickle Hall. Although its exact age is open to question, the young tree appears to have been happily growing in this location for at least two years. 

The parent toothache tree is not far away, at the southwest corner of Mickle Hall. Professor Leuck planted three toothache trees in this spot, with only one surviving today. You can read about those trees on an older blog post, found here.

We first took notice of our volunteer toothache tree during the summer. The little tree had grown tall enough to make itself visible, rising above a tangly, prickly mess of dewberry vines.

Today, we cleared away the dewberry vines (bring your gloves for this job) from the toothache trunk in order to take a good look at the young specimen. There was a noticeable lean in the trunk.

Measures were taken to correct the lean: the trunk was secured to a single post in order to encourage good posture. A ruler was stuck in the ground to give us an idea of the tree's height⸺the volunteer toothache is already more than 2 feet tall.

Our little toothache tree is fully equipped with the characteristic spines. Ouch!

Tree of the Week: Toothache Tree (Zanthoxylum clava-herculis)

The toothache tree (Zanthoxylum clava-herculis) is known for its peculiar bark. Medicinal use of the inner bark is the origin of the common name 'toothache tree': chewing the inner bark numbs the gums, relieving the pain associated with a toothache. The outer bark of this tree has resulted in another common name: Hercules' club. The whole tree is covered in spines, but the trunk of the tree and its older branches have large thorns, giving the trunk and branches a particularly aggressive appearance, recalling the deadly weapon used by the Greek hero Heracles.

There are three individual toothache trees in the arboretum collection, all growing at the southwest corner of Mickle Hall. Two of the three trees were purchased from Woodlanders Nursery out of Aiken, South Carolina. They were planted in 1989. More than a decade later, Ed Leuck added an additional specimen, collected in Shreveport, from along Clyde Fant Parkway. Interestingly, the younger tree has significantly outpaced the two trees from South Carolina. The specimen from Shreveport is over twice the size of the 1989 plantings.

This is the southwest corner of Mickle Hall, the entrance to the basement of the building. The youngest toothache tree is almost two stories tall, reaching the first floor windows. French mulberry (Callicarpa americana) and coral bean (Erythrina herbacea) grow in its shade. The older two toothache trees are nearby (not pictured), and half the size of the younger tree.

Trunk detail: mottled bark with thorn-tipped corky knobs

Bark detail

Branch with thorns in profile; branchlet also showing thorns

Cluster of unripe fruit

Zanthoxylum clava-herculis leaf detail

You can see additional photos of the arboretum's toothache trees here.

For more information about this species consult the following:
United States Department of Agriculture 
Louisiana Plant Identification and Interactive Virtual Tours (LSU AgCenter) 
Texas A&M Forest Service

Ptelea trifoliata

Zanthoxylum clava-herculis

The branches of Zanthoxylum clava-herculis are often covered in sharp spines, giving it the common name "Hercules' club."