The American smoketree, Cotinus obovatus Raf. (Anacardiaceae), has three distinct centers of distribution (Barkley 1937, Little 1977), and it is nearly restricted to limestone outcrops and rocky limestone soils throughout its range. Cotinus obovatus grows on hillsides and limestone outcrops on the Edwards Plateau of Texas (Correll and Johnston 1970), on limestone and dolomite cliffs and glades in the Ozark region of Oklahoma, Arkansas and Missouri (Steyermark 1940, Little 1943, Kucera and Martin 1957, Tucker 1976), and on rocky wooded limestone slopes in northern Alabama and adjacent Tennessee (Harper 1928, Shanks 1952, Clark 1971, Whetstone et al 1979). The species was listed as endangered in Kentucky by Branson et al (1981) and by Warren et al (1986).