Melicope haupuensis, a member of the Rutaceae (rue) family, is a tree about 8 m (26 ft) tall. The oval leaves, 5 to 13 cm (2 to 5.1 in) long and 28 to 56 mm (1.1 to 2.2 in) wide, are oppositely arranged. Flowers grow in clusters of 5 to 7 on stalks usually 2 to 7 mm (0.1 to 2.8 in) long, each flower on a stalk 1 to 3 mm (0.04 to 0.12 in) long. Female flowers are about 3.5 mm (0.14 in) long, dotted with oil glands, and covered with a dense mat of hairs. Fruits are distinct follicles (a dry fruit that splits open lengthwise), 9 to 11 mm (0.35 to 0.43 in) long, with a hairless exocarp and endocarp (outermost and innermost layers of the fruit wall, respectively).