Description from Flora of China
Piper hispidum Hayata (1911), not P. hispidum Kunth (1815).
Climbers to several m long, dioecious. Stems rooting at nodes, densely roughly rusty brown pubescent when young, sparsely pubescent when old, hairs usually curved toward stem apex. Petiole 0.5-2.5 cm, longest on stoloniferous branches, roughly pubescent, sheathed at base; leaf blade ovate or ovate-oblong, 3.5-5 × 2-3 cm, membranous, finely glandular, abaxially sparsely pilose on veins, adaxially sparsely pilose mostly between veins, with curved hairs, base cordate, slightly oblique, apex acute or obtuse; veins 5-7, apical pair arising 1-2 cm above base, others ± basal; reticulate veins conspicuous; leaf blades toward apex of stem long elliptic, oblong, or ovate-lanceolate, 7-11 × 3-4.5 cm, base oblique or semicordate, apex shortly acuminate. Spikes leaf-opposed. Male spikes 5.5-13 cm × 2-3 mm; peduncle ca. as long as or slightly longer than petioles of leaves toward apex of stem; bracts orbicular, 0.7-1 mm wide, peltate, abaxially glabrous, fascicled pubescent at insertion to rachis, stalk short. Stamens 2; filaments short; anthers subglobose. Female spikes 4-5.5 cm; bracts as in male spikes. Ovary subglobose, distinct; stigmas 4, linear. Drupe obovoid, distinct, ca. 2 mm in diam. Fl. Mar-Jul.
Material of this species has mostly been named as Piper arboricola but the type of that name is clearly conspecific with P. kadsura. Piper sintenense is very closely related to P. hongkongense, differing only in relatively minor quantitative characters, and the two taxa may prove to be conspecific. Piper laosanum C. de Candolle, from Laos, might be conspecific and thus would provide an earlier name.
* Forests, usually on trees and rocks; 1000-2500 m. Taiwan