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

Autumnal weather has arrived in northwest Louisiana. This week we experienced low temperatures in the 30s, and over the next several days we expect high temperatures above 80℉. Although the mosquitoes are still buzzing about, the overall drop in temperature means that we can start moving plants around without fretting too much about survival rate. Today, a young, volunteer toothache tree (Zanthoxylum clava-herculis) was transplanted to a better location and officially added to the arboretum catalogue. 

  

The volunteer toothache tree is pictured center. Some time within the past few years it germinated in the patch of dewberry (Rubus trivialis) on the west side of Mickle Hall, not far from the mature toothache tree. After the dewberry and yellow passion flower vines were pulled away from it, we could see the form of the young toothache tree: it is a little less than 2 feet tall, and it has a very long surface root.

 

This is a detail image of the toothache tree's long surface root. The little tree isn't connected to the soil at the base of its trunk, and it seems that the vines that had grown up around it were doing much of the work of holding it up straight.

 

Examining the volunteer toothache tree gave us another look at the giant swallowtail caterpillar (Papilio cresphontes). We talked about this species on our previous blog post.

 

 In this video we can see the caterpillar eating part of a toothache leaf. (The video also shows how windy it was today!) When humans chew on the leaves of this tree, we experience a tingling sensation in the mouth, and if we chew on enough of the leaves, we experience a numbing effect.

 

This large, chunky caterpillar with a very interesting color scheme was relocated to the nearby mature toothache tree.

 

This toothache tree only has shallow roots, with one particularly long surface root. Not much digging was required to remove the tree from the dewberry patch.

The root system is surprisingly sparse, especially considering how healthy the trunk looks.

 

The toothache tree was transplanted from the top of a hill to the bottom of a hill in the hopes that it will have access to more water. It appears to be all by its lonesome on the Fitness Center lawn. A black oak (Quercus velutina) and black willow (Salix nigra) are growing nearby.

 

Two metal stakes flagged with pink tape serve as protection against lawn mower damage, and the pine straw mulch will help the soil retain moisture. This individual was thoroughly watered after planting was complete, and the soil moisture will need to be monitored until the tree enters dormancy.

 

Leaves at the very top already started to droop from the stress of relocation. They will hopefully perk back up soon. This same thing happened to the two other toothache trees that were transplanted this past spring. You can read about them here. Both of those young trees survived the summer.