Hibiscus waimeae subsp. hannerae, a member of the Malvaceae (mallow, hibiscus) family, is a gray-barked tree, 6 to 10 m (20 to 33 ft) tall, with star-shaped hairs densely covering its leaf and flower stalks and branchlets. The circular to broadly egg-shaped leaves are 5 to 18 cm (2 to 7 in) long and 3 to 13 cm(1.2 to 5 in) wide. The strongly fragrant flowers are borne singly near the ends of the branches on flower stalks 2 to 3 cm (0.8 to 1.2 in) long. The calyx is tubular, 3 to 4.5 cm (1.2 to 1.8 in) long, with lobes 8 to 15 mm (0.2 to 0.6 in) long. The flaring petals are white when the flower opens in the morning but fade to pinkish in the afternoon. The petals, 4 to 6 cm(1.6 to 2.4 in) long, are basally attached to the stamina column to form a tube 1.5 cm (0.6 in) long. The exerted staminal column is 15 cm (6 in) long and reddish to crimson at the tip. The filaments arise in the upper half of the staminal column and spread to 2.5 cm (1 in) long. The fruit is a cartilaginous, egg-shaped capsule 1.8 to 2.5 cm (0.7 to 1.0 in) long and hairless.