Ochrosia kilaueaensis, a tree with milky sap in the Apocynaceae (dogbane) family is 15 to 18 m (49 to 59 ft) tall. Oblance-shaped to ob-elliptic leaf blades, 6 to 19 cm (2.4 to 7.5 in) long and 2.2 to 6.5 cm (0.9 to 2.6 in) wide, are arranged three to four at a node. Conspicuous secondary veins are almost perpendicular to the midvein. Numerous flowers are arranged in clusters and subtended by main flower cluster stalks divided into two sections: primary stalks (peduncles), 4.5 to 6.3 cm (1.8 to 2.5 in) long; and secondary branch stalks, 1.1 to 2.5 cm) (0.4 to 1 in) long. Each flower has a flower stalk (pedicel) 5 to 7 mm (0.2 to 0.3 in) long. The calyx is deeply 5-lobed and about 1 cm (0.4 in) long. The green-white, trumpet-shaped flowers have five lobes 12 to 15 mm (0.5 to 0.6 in) long fused at the base into a cylindric tube 7 to 11 mm (0.3 to 0.4 in ) long. Lance-shaped fruits, 4.5 to 4.9 cm (1.8 to 1.9 in) long and 2.4 to 2.5 cm (0.9 to 1.1 in) wide, have a fleshy inner layer, a stony single seed, and may be yellow-brown when mature.