Zanthoxylum americanum (Prickly Ash)

Plant Info
Also known as:
Genus:Zanthoxylum
Family:Rutaceae (Rue)
Life cycle:perennial woody
Origin:native
Habitat:part shade, shade; upland forest, floodplains, old fields, forest clearings
Bloom season:April - May
Plant height:15 to 20 feet
Wetland Indicator Status:GP: UPL MW: FACU NCNE: FACU
MN county distribution (click map to enlarge):Minnesota county distribution map
National distribution (click map to enlarge):National distribution map

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Detailed Information

Flower: Flower shape: 5-petals Cluster type: round

[photo of male flowers] Male and female flowers are on separate plants in round clusters, about an inch across, in the leaf axils of 1-year-old branches, with 2 to 12 flowers in a cluster. Flowers are green to reddish with a short stalk and 5 egg-shaped petals that stay appressed about the base; sepals are absent. Male flowers have 5 erect yellow stamens.

[photo of female flowers] Female flowers have 3 to 5 dark green ovaries, each with a long pale style, the styles converging at the tip. Flowers emerge before the leaves in early to mid spring.

Leaves and stems: Leaf attachment: alternate Leaf type: compound

[photo of leaves] Leaves are alternate and pinnately compound, 5 to 10 inches long with 5 to 11 egg shaped to lance-elliptic leaflets and a few small prickles along the underside of the leaf stalk. Leaflets are 1 to 2 inches long and half as wide, nearly stalkless with nearly smooth edges. The upper surface is dark green and smooth or with sparse hairs (especially when young), the lower surface pale green and hairy. Leaves give off a lemony scent when crushed.

[photo of trunks] Branchlets are brown to gray and mostly smooth or with a few sparse hairs, and a pair of sharp, 1/3-inch prickles just below the leaf axils that persist on older branches. Older bark is mostly gray or brownish, mostly smooth or roughish. Twigs give off a lemony smell when broken.

Fruit: Fruit type: capsule/pod

[photo of fruit] Fruit is a red, finely textured, round to egg-shaped capsule up to ¼ inch long that splits in half when mature, revealing a shiny black seed. Fruits mature from late July through August.

Notes:

Prickly Ash is likely quite familiar to anyone who has spent time exploring or hunting in Minnesota's forests and woodlots. The spreading, shallow root system will send up new suckers when not inhibited by competing vegetation, creating dense thickets of nearly impenetrable brush that tears at the hands, face and clothing. All parts of the plant produce a fragrant and pungent citrus-like oil and it has been used for a number of medicinal purposes, notably tooth aches. Anyone who has tried chewing on a twig or just a few fruits quickly experiences its bitter, numbing, and throat grabbing properties. A few have questioned whether it actually inhibits tooth ache pain or is merely so obnoxious as to distract the sufferer from anything else in the mouth. Prickly Ash has no relationship to either our large forest ash species or the mountain ashes.

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More photos

Photos by K. Chayka taken at Rice Creek Trail Regional Park, Ramsey County. Photos courtesy Peter M. Dziuk taken in Anoka County.

Comments

Have you seen this plant in Minnesota, or have any other comments about it?

Posted by: Travis - Near Crosslake
on: 2015-10-17 00:05:07

South of the city of Crosslake is a bar called the Cedar Chest. South of the cedar chest is Big Pines Trail, the first left. The first right on Big Pines Trail leads to a logging road as the first turn off the left. What appears to be prickly ash grows on either side. I would love to hear of other locations.

Posted by: Mike S. - Hubbard County
on: 2016-02-24 12:55:06

We have this shrub spreading rapidly on our property. We first encountered in 10 years ago when clearing a trail through our woods. It was a small patch, less than 50 ft2. Now it has spread to close to 1/2 an acre. It has become inpenetrable and is shading out other shrubs. Our woods have alot of overmature basswood that is subject to blowdown, which is creating openings for prickly ash to spread.

Posted by: Rachel F - Ramsey County
on: 2016-08-19 21:00:59

I've found some here and there in the New Brighton/Arden Hills area, but none large enough to produce berries. It's the northernmost member of the citrus family and the berries are interchangeable with the Chinese spice known as "szechuan pepper." I did find some at Lebanon Hills recently that were producing berries, so we'll see if it's worth the numerous scratches and thorn pricks it took to harvest them!

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