Native Plants

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Friday - September 19, 2014

From: Pittsford, MI
Region: Midwest
Topic: Plant Identification, Medicinal Plants, Shrubs
Title: Shrub with thorns, black fruit and citrus fragrance in Michigan
Answered by: Nan Hampton

QUESTION:

I'm not sure that my plant is a native, but I'm hoping to find some answer. There is a small patch of roadside shrubs on my property which I've been unable to identify. They have simple opposite smooth edged leaves and prominent thorns. The identifying characteristic is that in the fall they produce clusters of seed pods which are smaller than peas. The pods are perfectly round, start our orange or red and turn black. The seed pods, and the leaves as well, when crushed produce a very strong smell like orange peel.

ANSWER:

Mr. Smarty Plants thinks that this is the native shrub, Zanthoxylum americanum (Common pricklyash). Here are photos showing the foliage of the shrub and more information from Illinois Wildflowers. It is a member of the Family Rutaceae (Citrus Family) and as Illinois Wildflowers says: "Both the crushed foliage and fruits are highly aromatic, somewhat resembling the fragrance of lemon peels." You can see more photos from the Herbarium, Cofrin Center for Biodiversity, University of Wisconsin–Green Bay and also from the Robert W. Freckman Herbarium, Plants of Wisconsin, Univeristy of Wisconsin.

You may have noticed the common name "Toothache tree" associated with this plant on our species page. If you visit the University of Michigan–Dearborn's Native American Ethnobotany database and enter "Zanthoxylum" in the Search String slot, you will see that various preparations of the bark were used to treat toothache by a number of Native American tribes ( e.g., Alabama, Comanche, Iroquois). This database shows many other medical remedies for this plant that were used by Native Americans. Plants for a Future also cites medicinal uses and says the seeds can be used as a pepper substitute.

Zanthoxylum hirsutum (Texas hercules' club) that is native to Central Texas (where the Wildflower Center is located) also has "toothache tree" as one of its common names. Another of its common names is "tickle-tongue" and "tingle tongue". A quote from the species page in our Native Plant Database says: "Bark, leaves, and fruit all numb the mouth and have been used to treat mouth pain, including toothache, hence its common name, Toothache Tree." This particular Mr. Smarty Plants can testify that especially the new leaves when chewed numb the tongue and make it tingly. I haven't tried the fruits but apparently they can be substituted for Szechuan peppers that are used in Chinese dishes. Szechuan peppers are identified as several species in the same genus, Zanthoxylem (e.g., Z. simulans, Z. bungeanum, Z. schinifolium). I couldn't find any references that said the leaves or berries of Z. americanum numb the tonugue.

From the Image Gallery

Common pricklyash
Zanthoxylum americanum