Cyanea duvalliorum is a short-lived tree, 13 to 20 ft (4 to 6 m) tall, producing distinctive juveniles. Trunk of adults is 4 to 21 cm (1.5 to 8 in) diameter at base, branching about 1 m (3 ft) above ground, the 4 to 11 branches diverging from trunk at a 45 to 60 degree angle, ascending, sometimes branching sparingly and armed with stout conic prickles. Lamina are elliptic or oblanceolate, 31 to 53 cm (12 to 21in) long and 10 to 20 cm (4 to 8 in) wide, upper surface dark green and glabrous and lower surface pubescent on veins with short, stiff hairs. Racemes are 6- to 10-flowered, the flowers all blooming simultaneously. Corolla is white, 38 to 47 mm (1.5 to 1.9 in) long, with dorsal corolla lobes spreading and ventral lobes deflexed. Berries are bright orange, ellipsoid, 17 to 21 mm (0.7 to 0.8 in) long, 10 to 15 mm (0.4 to 0.6 in) in diameter, crowned by the persistent calyx lobes. Seeds are brown, broadly ellipsoid, 0.7 mm (0.03 in) long, 0.5 mm (0.02 in) in diameter.