This well-known dioecious Chinese tree was first introduced to Ky. in the 1840s by Henry Clay (Del Tredici 1981; records of Ashland in FAYE), and it is now widely planted across much of the state. Local naturalization has only been reported from JEFF, where occasional seedlings have been found in Cherokee Park (J. Wysor, pers. comm.), and a self-sown tree 6 m tall has been found along a fence row (MM for APSC). Squirrels will sometimes take seeds after flesh of the fruits is rotted or washed off (Del Tredici 1989; L. Winter, pers. comm.); The largest known tree in Ky. (with dbh > 17 dm) may be at Cave Hill Cemetery (JEFF); this is a male tree, but one branch has turned female, apparently in association with a high witches broom infection (P. Cappiello, pers. comm.). However, two trees in Lexington (FAYE) may be even larger, at 255 North Broadway and 341 Madison Place: both are ca. 1.5-2 m dbh, 30-35 m tall and 25-30 m wide in 2020. Trees may also persist through sprouts from embedded buds from cotyledonary axils (Del Tredici 1992). Local sex change within dioecious trees is a rare event that has also been convincingly documented in Japan (Nagata et al. 2016). Another mysterious aspect of Ginkgo trees is their occasional deviation from diploid condition (2n = 24), including haploids, triploids and tetraploids (Smarda et al. 2018). The chemistry of Ginkgo is diverse and unusual, including triterpene trilactones and flavonoids that have reported medicinal value, especially in neurological disorders (Ude et al. 2013); but it also includes "ginkgotoxins" (phenolic pyridoxine derivatives with long alkyl chains) that have some similarity to the allergens in Toxicodendron. The putrid smell of Ginkgo fruits is largely due to butanoic acid and hexanoic acid, which may have attracted scavenging mammals and birds in the Cretaceous era, when the species was much more widspread across the Northern Hemisphere (Del Tredici 1989, 2008).