This tree was originally concentrated in east-central states, especially Appalachian and Ozarkian regions, but it is now widespread across humid temperate regions of the world (W, Y; Little 1971, Ladd & Thomas 2015, Li et al. 2018). [Self-pollination is less successful than cross- but apomixis remains unknown.] Its geographic and ecological range has been expanded greatly due to plantings and escapes; the species is particularly successful on disturbed submesic soils of moderate to high fertility (including sufficient phosphorous), where its nitrogen-fixation can maintain high productivity (e.g. Belt 2015). Although the species is generally considered diploid (2n = 20), a tetraploid form has been discovered in Korea and propagated for some superior qualities in East Asia (Meng et al. 2016). In Ky., early records indicate that pseudoacacia was locally common within the Bluegrass region at the time of settlement (Campbell 1987), but uncommon to absent in western regions of the state (Barton 1919). The only pre-1960 records from west of the Bluegrass and Knobs appear to be a few 1920-41 colls. from hilly transitions to the Coastal Plain in MCRA, CALL &TRIG. In the central Bluegrass, Short (1828-9) noted: "My own observations do not agree with those of M. Michaux in regard to habits of this tree; for although it does occur in profuse abundance in this and other richest lands of Kentucky; yet I have found the largest and most thrifty stocks on the Ohio river in Boon county, seventy miles north of Lexington, where the soil is greatly inferior to that in this vicinity... Within the last few years, however, this excellent tree has sustained serious injury from the depredations of an insect, which penetrates to the very centre of the wood permeating its whole substance with large hollows; in consequence of which many of the finest trees have become destroyed. Where planted in town the locust tree flowers about the 1st of May, those in the country are observed to be a week or ten days later." The species is often much browsed by herbivorous mammals (e.g. Burner et al. 2008, Brinks et al. 2011, Katona et al. 2013, Rossell et al. 2013); it has become a staple for feeding to rabbits (e.g. Bhatt et al. 2010). However, the toxalbumin "robinine" (a ribosome-inactivating protein with lectin base) is present in most parts of the plant, and it can sicken animals (at least some livestock) within an hour of ingestion (Oakes & Wang 2016). Also, plants are often able to resprout aggressively after browsing, and can then sometimes increase relative to other browsed species (e.g. Bressette et al. 2012). Burning alone may not generally prevent invasion, unless repeated at 1-3 year intervals; once small clonal stands are established within old fields or grassland the vegetation appears to become much less flammable due to rapidly decomposing litter and nitrogenous ground cover.