Pterocarya stenoptera C. de Candolle var. tonkinensis Franchet, J. Bot. (Morot) 12: 318. 1898.

Trees to 30 m tall. Leaves even-pinnate, rarely odd-pinnate, 18 cm or more; petiole 4.5-7 cm, glabrescent; rachis wingless, sometimes ridged or sulcate, pubescent or glabrescent; leaflets 6-14, sessile, ovate or elliptic-ovate, 9-17 × 3-7 cm, abaxially glabrous except for hairs along midvein and secondary veins, base oblique, rounded or broadly cuneate, apex acute to acuminate. Fruiting spike 13-30 cm. Nutlets rhomboid, 6-7 mm, glabrous; wings linear, 1-1.7 cm × 2-6 mm. Fl. Mar, fr. May-Oct.

Shares many features with Pterocarya stenoptera, but lacks wings on the rachis and has a more southerly distribution with earlier flowering and fruiting. Transitional forms occur where the ranges of two species overlap.

Wet areas along mountain streams; 200-1200 m. S Yunnan [Laos, Vietnam]