This variable species (2n = 34, 51, 68) of the central states may intergrade with angustifolia or coronaria in Ky., which lies across zones of overlap between all three taxa (FNA 9). Relatively pure ioensis appears concentrated in or near the gravelly hills of the Mississippian Embayment, where it may be a remnant from the open grassy woodlands that occurred here before settlement. See also notes under coronaria. M. ioensis differs from angustifolia and coronaria as follows (FNA 9, W): leaves persistently pubescent beneath (versus usually glabrous or nearly so except for villous veins); pedicels and hypanthium pubescent (versus usually glabrous or with sparse hairs). Also, flowers tend to be larger (mostly 3.5-5 cm wide versus 2-3 cm); and fruits tend to be larger (mostly 2-3 cm wide versus 1-2 cm). There has been considerable interest in development of cultivars with superior floral features (Fan et al. 2019). The native apples form a distinct section (Chloromeles), although their division into species remains problematic. They differ from domestica (= pumila), prunifolia and baccata as follows (FNA 9, W): cores of pomes not enclosed at apex (versus enclosed); sclereids abundant surrounding core (versus absent or sparse); petals usually pink but fading to white (versus usually white but rose in bud); anthers rose, pink, salmon, or purple before dehiscence (versus yellow); leaves folded lenthwise in bud (versus curled inwards), the blades of vigorous shoots often lobed (versus strictly unlobed); twigs often thorny (versus usually not). Apparent hybrids of Chloromeles with other Malus are reported but remain infrequent or local (McVaugh 1943; K, W). Based on nuclear DNA, Chloromeles is allied with some Malus (sensu lato) species of southern Europe and southeast Asia; but plastid DNA is more similar to Sorbus, Aronia and Cydonia (Liu et al. 2022).