Shrubs or trees, 2–200 dm. Stems 1+ (derived from root shoots), erect; bark dark brown, reddish brown, or gray, firm, platy or scaly; long and short shoots present; thorns present (modified short shoots); glabrous, glabrescent, villous, densely puberulent, or tomentose. Leaves deciduous [semipersistent], cauline, simple, shoot dimorphism, long- and juvenile-shoot leaves usually larger and more deeply serrate (lobed) than short-shoot leaves; stipules deciduous (or persistent on vigorous shoot leaves in M. baccata), basally adnate to petiole, linear-lanceolate to lanceolate, sometimes filiform, membranous, sometimes herbaceous, margins entire, serrulate, glandular-serrate, sparsely glandular-denticulate, or white-ciliate; petiole present; blade elliptic, ovate, obovate, triangular-ovate, oval, lanceolate, ovate-oblong, or oblong, (2–)4–12 cm, membranous or leathery, margins flat, sometimes lobed, dentate, serrulate, serrate, doubly serrate, crenate, or sometimes entire, venation pinnate (craspedodromous when lobed, camptodromous when unlobed), surfaces glabrous or tomentose. Inflorescences terminal on short shoots, 2–12-flowered, flat-topped panicles, glabrous or tomentose; bracts present (absent in M. fusca), caducous, ovate, linear-lanceolate, membranous, glabrous; bracteoles present. Pedicels present. Flowers bisexual (occasionally andromonoecious in M. halliana), opening with leaves, perianth and androecium epigynous, 15–50 mm diam.; hypanthium campanulate, size not recorded, glabrous or tomentose; sepals 5, reflexed to wide spreading, triangular, triangular-lanceolate, triangular-ovate, or lanceolate; petals 5 (or more in M. halliana), white, pink, or red, suborbiculate, obovate, narrowly or oblong-obovate, ovate, or ± elliptic, base clawed; stamens 15–50, unequal, usually shorter than, rarely equal to, petals; carpels 3–5, connate, adnate to hypanthium, styles 3–5, emerge from base of hypanthium, basally connate, glabrous or tomentose basally; ovules 2. Fruits pomes, green, yellow, or red, globose, depressed-globose, obovoid, or oblong, 6–50(–70) mm diam., glaucous, waxy, punctate; flesh homogeneous, stone cells adjacent to carpels and epidermis; hypanthium persistent; sepals persistent or deciduous, erect or reflexed; carpels cartilaginous; styles persistent or deciduous. Seeds 2 per carpel, light, dark, or reddish brown, smooth. x = 17.