Plantago hawaiensis of the Plantaginaceae (plantain) family, an herb which grows from a stout short stem, has thick, leathery, narrowly oval or oblong basal leaves 7.5 to 22 cm (3 to 8.7 in) long and 1.5 to 3.2 cm (0.6 to 1.3 in) wide. The flowering stalk is 20 to 90 cm (7.9 to 35 in) long and topped by a spike 15 to 23 cm (5.9 to 9 in) long. Each upward pointing flower, subtended by a single bract 2.1 to 2.6 mm (0.08 to 0.1 in) long, has a four-lobed calyx 1.6 to 2.2 mm (0.06 to 0.09 in) long and a trumpet-shaped corolla about 1 mm (0.04 in) long. The capsule, 2.6 to 4 mm (0.1 to 0.2 in) long and projecting from the calyx, opens to release four to six dull black seeds 1 mm (0.04 in ) long and winged on one end.