This tree ("Chinese or little leaved elm") has been widely planted across temperate North America, especially as an urban street tree, and it has locally escaped (K, W). The records mapped here appear to be from self-seeded plants, and seedlings are locally common near planted trees. But it is not clear if the species will become truly naturalized outside of urban environments. U. parvifolia is sometimes confused with pumila (W, Y). Well-developed leaves on mature trees are generally smaller (mostly 3-5 x 1.5-2.5 cm versus 4-7 x 2-3.5 cm), with more asymetrically oblique bases and more forked veins (usually 4-9 per side versus 1-3). Bark of young vigrous trees is distinctly platey and reddish to orange in fresher exposures (versus furrowed and mostly greyish); however, older or larger trees may loose this character. Flowering usually occurs in Aug-Oct (versus Feb-Apr). The species is generally considered superior to pumila for ornamental use in eastern states, with fewer problems from fungi and insects (missouribotanicalgarden.org).