Cyanea marksii, a palm-like tree in the Campanulaceae (bellflower) family, is 2 m (6.6 ft) tall. Leaves are dimorphic. Leaves of juvenile plants are obovate to oblong, blades 13 to 18 cm (5 to 7 in) long, 5.5 to 7 cm (2.2 to 2.8 in) wide, upper surface armed with prickles, lower surface pubescent and prickly, margins with hardened, pointed teeth, apex blunt to sharp-pointed, base rounded to blunt, petioles 2.5 to 4 cm (1 to 1.6 in) long. Leaves of adult plants are oblong to oblanceolate, blades 25 to 31 cm (9.8 to 12 in) long, 8 to 12 cm (3 to 4.7 in) wide, upper surface smooth or with sharp projections, lower surface pubescent, margins with minute hardened prickles, apex sharp-pointed, base wedge-shaped, petioles 8 to 14 cm (3 to 5.5 in) long, with sparse sharp projections. Inflorescences are 5- to 8-flowered, clustered among the leaves, calyx lobes narrowly triangular, and petals are blackish purple externally and white within. Berries are ellipsoid, 14 to 18 mm (0.6 to 0.7 in) long, crowned by persistent calyx lobes.