Cyanea obtusa is a shrub in the Campanulaceae (bellflower) family approximately 2 to 5 m (6.6 to 16 ft) tall, with branched pubescent (hairy) stems. Leaves are oblong to oblanceolate, with blades 15 to 30 cm (6 to 12 in) long and 4 to 9 cm (1.6 to 3.5 in) wide, with the upper surface green and sparsely pubescent, and the lower surface pale green and densely pubescent. Inflorescences are 6- to 12-flowered, densely pubescent, with flower stalks 2 to 5 cm (0.8 to 2.0 in) long. The hypanthium (cup structure formed by fusion of calyx and corolla) is obovoid, with narrowly triangular calyx lobes 1 to 2 mm (0.04 to 0.08 in) long. The corolla is purplish, 3 to 3.6 cm (1.2 to 1.4 in) long, 1.5 to 3 mm (0.06 to 0.1 in) wide, and is also densely pubescent. Berries are not described.