This variable southeastern species (2n = 34 or rarely 68) is often difficult to distinguish from coronaria or ioensis (FNA 9), and several records mapped here may be from intermediate plants. In Ky., most records are from the Appalachian Cliff Section, especially in southern sections. There is a remarkable cluster of records from the less rugged uplands of MCRE and WHIT, where open grassy or brushy conditions appear to have occurred before settlement. See notes under var. puberula and M. coronaria. M. angustifolia differs from coronaria as follows (FNA 9, W): leaves ca. 2.5-8 x 1-4 cm wide (versus 4-10 x 2-7 cm), with L/W mostly 2-2.5 (versus 1.5-2), usually subacute to obtuse at apex (versus obtuse). Its flowers (ca 2.5-4 cm wide) and fruits (mostly 1.5-3 cm) are generally intermedate in average size between ioensis and coronaria. The native species of Malus, especially angustifolia, appear more resistant than cultivated apples to the bacterial "fire blight", which may have originated in North America (Dougherty et al. 2021). In addition to general forest succession, causes of reduction in native Malus may involve infection by the "cedar apple rust" that overwinters on Juniperus (Zhao et al. 2020).