Zanthoxylum americanum (Prickly Ash)
|Also known as:|
|Life cycle:||perennial woody|
|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):|
|National distribution (click map to enlarge):|
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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.
Leaves and stems:
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.
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.
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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Where to buy native seed and plants ↓
- Prickly Ash plant
- a dense thicket of Prickly Ash
- twig, prickles and bud scars
- emerging leaves
- small shrubs in late may
Photos by K. Chayka taken at Rice Creek Trail Regional Park, Ramsey County. Photos courtesy Peter M. Dziuk taken in Anoka County.
Have you seen this plant in Minnesota, or have any other comments about it?