This infamous, malodorous Chinese tree was introduced to North America in 1784 as an exotic ornamental (Kasson et al. 2013). But it has become widely naturalized in thin woods, edges and abandoned built-up sites, especially where repeated cutting or browsing occurs. The first report from Ky. that suggests naturalized status was by Hussey (1876). During recent decades, it appears to have increased rates of invasion into forests, sometimes colonizing gaps a mile or more from parent trees (A. Berry, pers. comm.). It is remarkably persistent through widely spreading root suckers that proliferate after larger stems are removed. The complex chemistry of this species includes quassinoids (triterpene lactones derivatives of Simaroubaceae) that have diverse pharmaceutical applications (De Martino & De Feo 2008); they also appear to be involved in allelopathy (Heisey 1996). There are also alkaloids of canthin-6-one and carboline type. Noxious smell and dermatitis may be associated with 2,6-dimethoxybenzoquinone. Although this invasive species has had little problem from pests or pathogens in North America, some recently introduced insects may become significant consumers (Dara et al. 2015, Hoebeke et al. 2017). The "spotted landtern fly" uses Ailanthus as a preferred host, as well as many other woody species, especially in the order Sapindales and in Vitaceae (Liu 2019, Barringer & Ciafré.2020). This pest has spread rapidly across east-central states since first detection in 2014, but it does not yet appea to have caused signfiicant declines in the Ailanthus populaion.