Description from Flora of China
Climbers glabrous throughout, dioecious. Stems rooting at clearly enlarged nodes, ridged. Petiole ca. 1-3(-4) cm, many striated, very shortly pubescent, sheathed at base only; leaf blade cordate-orbicular, 6-10(-15) × 5-8(-15) cm, papery to ± leathery, both surfaces glaucous and glabrous, base cordate, sometimes peltate or subpeltate, apex cuspidate, mucro ca. 15 × 3-4 mm; veins 5, slender, prominent on both surfaces. Spikes leaf-opposed. Male spikes white, ascending, 5-8 cm; peduncle 0.6-1.5 cm. Female spikes 1-2.5 cm; peduncle ca. 1 cm. Stigmas 3 or 4. Drupe red, globose, ca. 2 mm in diam. Fl. Aug.
This taxon has sometimes been named as Piper philippinum Miquel (e.g., in Fl. Taiwan, ed. 2), following the account of Piperaceae in the Philippines by E. Quisumbing (Philipp. J. Sci. 43: 1-246. 1930). However, F. A. W. Miquel’s protologue of P. philippinum (Syst. Piperac. 322. 1843) clearly excludes P. kwashoense as described by Quisumbing because it refers to a plant with 5-veined leaves, lax female inflorescences 10-12 cm long, and ovoid fruits 4-5 mm long and apparently free from the rachis. The mistake seems to have come from Miquel, who based the protologue on a female plant, "Cuming in herb. de Lessert 1642," and then added a note that another collection, Cuming 912, might be the male of the same species although it did have a number of differences. This latter collection is much more widely distributed in herbaria, and P. philippinum has been interpreted as if Cuming 912 were the type.
* Lowland forests. S Taiwan