Shrub c. 1 m, glabrous except for parts of the inflorescence. Leaves clustered at the ends of the branches; Inflorescence a terminal compound umbel, c. 10 cm ø, peduncle stout, bearing ovate bracts c. 1 mm long; Petals and stamens unknown. Ovary 4-celled. Fruit ovoid, 4-ridged when dry, 7 by 5 mm.
Asia-Tropical: Philippines (Philippines present), Catanduanes present
Malesia: Philippines (Catanduanes).
Together with 10. O. caudatum and 11. O. heterophyllum this species forms a small group with leaves composed of lyrate leaflets. Although the foliage is similar (though not identical), the inflorescences are distinctive. In O. heterophyllum the rays are short, resulting in a compact compound umbel; in O. caudatum there are few rays (10 or fewer); in O. catanduanense there are many, relatively long rays, resulting in a large, diffuse compound umbel. Since O. catanduanense and O. caudatum are known only from the type collections, the range of variation of these species is not known, but the inflorescence differences justify the retention of all three species.