Coefficient of Conservatism:
Coefficient of Wetness:
Sometimes in upland deciduous forests, but usually in moist forests and thickets, even swamps, along streams and river banks.
Like Ptelea trifoliata, this species has oils that have given it reputed medicinal properties. The plant is usually a tall shrub, and spreads readily by suckers, forming large, spiny thickets. Vegetative specimens might superficially resemble Robinia pseudoacacia in the spiny stems and pinnately compound usually sparsely pubescent leaves. In Zanthoxylum americanum, the leaflets are ovate, ± acute but notched at the tip with a gland but without a mucro, sessile or nearly so. In Robinia, the leaflets are more elliptic, rounded at the tip but with a small mucro (even if somewhat notched), each with a distinct petiolule-pulvinus.
The forma impuniens Fassett, entirely unarmed, has been collected in Eberwhite Woods, Ann Arbor (Washtenaw Co.)