Recently, the native shrub or small tree Aralia spinosa has been reported from the northeastern United States farther north of its traditional range, while the Asian shrub A. elata has been reported to be naturalizing across the same region. Herbarium and field studies have clarified the current ranges of A. spinosa and A. elata in the eastern United States, with almost all recent reports of A. spinosa in the northeastern United States north of Maryland and Delaware being based on misidentifications of A. elata. Aralia elata is well established and rapidly spreading throughout all 25 counties in the New York metropolitan area. The most reliable characters for separating the two species are the length of the central inflorescence axis, fruit size, and seed size. Many herbarium specimens of these woody Aralia species cannot be confidently identified to species because they lack or have incomplete inflorescences/infructescences. Proper preparation of voucher specimens requires at a minimum the collection of the proximal portion of the inflorescence/infructescence.