Schiedea adamantis is a short-lived perennial shrub in the Caryophyllaceae (carnation) family is endangered and endemic to Oahu. Wagner: It is an erect, glabrous shrub, 30 to 80 cm (1 to 2.6 ft) tall, with internodes usually 1.0 to 1.5 cm (0.4 to 0.6 in) long. Leaves are opposite, elliptic to elliptic-oblanceolate or oblanceolate and 1.5 to 3 cm (0.6 to 1.2 in) long and 0.4 to 1.2 cm (0.15 to 0.47 in) wide. Leaves are 1-nerved with margins thickened and revolute, apex is acute or sometimes acuminate, and gradually tapering to the base. Flower are perfect or pistillate (and then plants are gynodioecious), in narrow, paniculate cymes. The inflorescence is 5 to 8 cm (1.9 to 3.1 in) long, bracts are green, sometimes purple-tinged and subulate. Stamens are 10, represented by staminodes in pistillate flowers. Capsules are 3.5 to 5 mm (0.14 to 0.2 in) long, dehiscent by as many valves as styles. Seeds are reddish brown, reniform and compressed, about 0.8 mm (0.03 in) long.