This is a largely northeastern species, extending south along the Appalachians, especially at higher elevation. There has been some confusuon with arborea. A, laevis has been generally distinguished from arborea as follows (F, Cr, FNA 9): leaves glabrous or nearly so (versus tomentose below at least when young), deeper green "with a prominent coppery-red cast that disappears before maturity" (Cr); flowering a little earlier, and with leaves already about half-grown (versus usually much less than half); pedicels usually up to 1.5-3 cm (versus 1-2 cm); fruits becoming relatively dark, sweeter and averaging larger (8-15 mm versus 6-10 mm or only 4-5 mm in dry years). Distinct populations of laevis may not be well-developed in Ky., and confirmed records are restricted to Appalachian regions, with a concentration in the Cumberland Mts. Records of laevis from western regions are dubious, although B reported it from LYON; and there are colls. from the western Highland Rim of Tenn. in Cheatham Co. (R.L. Jones #1781 at EKY) and Perry Co. (R. Kral #85843 at UCHT). The species appears to be most distinct at higher elevations of the Southern Appalachians, where trees often reach 10-15 m tall and occasionally up to 25 m. Typical plants may be generally diploid but a range of numbers has been reported: 2n = 30, 34 and 36 (Robinson & Partanan 1980; FNA 9). Diploids are reportedly concentrated in the southern Appalachians, and most plants investigated further north or west, including all of Ky., are tetraploids, with 2n = 68 (Burgess et al. 2015; C. Campbell, pers. comm.). These tetraploids may have originated in part from diploid laevis crossed with diploid arborea, and then reproducing partly through apomixis. There are also hybrids of garden origin (X grandiflora Rehder) that have been widely planted; these plants tend to grow poorly in compacted eutrophic soils of urban areas.