This widespread variable species extends from the Rockies to the Alantic but it is most common in the Great Plains and midwest (Latting 1961). In Ky. it is locally abundant on more rocky banks of the Ohio River and larger tributaries. It is less common inland, but does appear to be native in some remnants of native grassland or open woodland along smaller streams and on adjacent uplands with base-rich soils. Some plants along rights-of-way in Ky. may be adventive. D considered the species largely adventive in Ind. and Ohio, but Riddell listed it for Ky. as early as 1835. Recent local increases might have been alllowed by local reductions in livestock or deer, especially in developed lowlands or suburban areas where browsing could have previously limited the species. D. illinoensis is well-known to be preferred forage by rabbits (C. Sither, pers. comm.) and ungulates (Gm; Schweitzer et al. 1993; R. Seymour, pers. comm.). Also, its seeds are avidly consumed by diverse birds and small mammals. Roots contain tryptamine alkaloids that may inhibit growth of competing plants (Thompson et al. 1987) ); these alkaloids also have a tradition of psychoactive use by native peoples (Ott 2012). The common nitrogen-fixing bacterium of D. illinoensis is a newly described species that is also important in some beans and peanuts (Beyhaut et al. 2006). Although leaves are not sensitive to touch, pinnae bend down and leaflets fold together in pairs during the night (Latting 1961, Luckow 1993; and pers. obs.).