Plants 1–25 cm. Roots fusiform; rhizomes creeping, frequently with a few tubercles at nodes. Stems 1–2, glabrous, 1–2-branched or unbranched. Basal leaves petiolate, petioles 2–10 cm; blade ovate-triangular, 2–4 × 1.5–3.5 cm, ternate-2-pinnate; ultimate segments flabelliform or lanceolate, 5–15 × 3–8 mm. Cauline leaves 1–2, ternate-1–2-pinnate or ternate; ultimate segments lanceolate or elongate-linear, 10–25 × 2–3 mm. Umbels 2–3 cm across in flower, to 7 cm in fruit; bracts absent (occasionally 1, minute); rays 5–25(–30), 1.5–3 cm; bracteoles 1–3, 0.3–2 mm; umbellules 1–2(–3)-flowered; pedicels 0.2–2.5 mm. Calyx teeth minute, ca. 0.1 mm, or obsolete. Petals white, oblong, apex acute. Stylopodium low-conic; styles ca. 0.2 mm, shorter than stylopodium. Fruit oblong ovoid, 2–2.5 × 1–2 mm; ribs filiform; vittae 1–2 in each furrow, 2 on commissure. Fl. and fr. Apr–Aug.

Literature references to Pternopetalum tanakae occurring in the Himalayas are based on misidentification of material that should correctly be ascribed to P. subalpinum.

Forests; 700–1600 m. Anhui, Fujian, Jiangxi, Zhejiang [Japan, Korea].