Lianas. Leaves opposite, long petiolate. Cymes irregularly branched with racemelike cymules, long pedunculate. Calyx glands 5. Corolla shallowly bowl-shaped, divided halfway; lobes overlapping to right. Corona lobes 5, inserted on gynostegium, erect, fleshy, oval, turgid, shorter than anthers. Anther appendages membranous, ovate, overlying stigma head; pollinia 2 per pollinarium, oblong, horizontal, caudicles obliquely ascending. Stigma head discoid. Follicles broadly fusiform, mesocarp fibrous. Seeds ovate.

One species: Cambodia, China.

Most material available has poorly preserved flowers which perhaps explains the original description of the pollinia as pendulous. Reexamination of paratype material with quite well-dried flowers has shown that they are horizontal. There is little, apart from fruit morphology, to distinguish Merrillanthus from Tylophora, especially T. augustiniana, which differs only by the laxer inflorescences and much smaller flowers (its fruits are not known).