Zanthoxylum americanum
Common name: 
Prickly Ash
Northern Prickly Ash
Toothache Tree
zan-tho-ZI-lum a-mer-i-KA-num
Native to (or naturalized in) Oregon: 
  • Deciduous shrub or small tree, 15-25 ft (4.5-7.5 m) tall, reproduces from root shoots and can form thickets.  Leaves alternate, pinnately compound (odd), 5-11 leaflets on a prickly central stalk 10-20 cm long, ovate to elliptic, two opposite spines on the stem at or below the point of petiole attachment.  Flowers small, greenish, in small axillary clusters, appear before the leaves; dioecious - male and female flowers on separate trees.  Fruit small, 4-5 mm across, bright red, containing 1-2 shiny black seeds.
  • Sun or shade, shade-tolerant.  Effective as a barrier plant.
  • Hardy to USDA Zone 3         Native from Quebec to South Dakota and south to Oklahoma and north to Virginia.  A related species, Zanthoxylum clava-herculis, Hercules' Club or Southern Prickly Ash, is native to Virginia and along the coast to northern Florida and west to Texas and Oklahoma.
  • americanum: of America
  • Toothache Tree: oil from bark and fruit once used as a remedy for toothaches, rheumatism and other afflictions.
  • Portland, Oregon: Hoyt Arboretum 
Click image to enlarge
  • leaf


  • stem, leaflets, and spines

    stem, leaflets, and spines