The Mammee tree is 18–21 m (59–69 ft) high and is similar in appearance to the southern magnolia (Magnolia grandiflora). Its trunk is short and reaches 1.9–2.2 m (6 ft 3 in – 7 ft 3 in) in diameter. The tree's upright branches form an oval head. Its dark-green foliage is quite dense, with opposite, leathery, elliptical leaves. The leaves can reach 10 cm (3.9 in) wide and twice as long.

The Mammee flower is fragrant, has four or six white petals, and reaches 2.5–4.0 cm (0.98–1.57 in) wide when fully blossomed. The flowers are borne either singly or in clusters of two or three, on short stalks. A single flower can have pistils, stamens, or both, so flowers can be male, female or hermaphrodite on one tree.