Description from Flora of China
Hymenidium heracleifolium (Franchet ex H. de Boissieu) Pimenov & Kljuykov.
Plants 40–80 cm. Root dark brown, long-conic. Stem ribbed. Basal and lower petioles to 20 cm, flattened, membranous-winged, sheaths narrow-oblong; blades broadly triangular-ovate, 8–12 × 8–12 cm, 3–5-lobed or 2-ternatifid; ultimate segments ovate or narrow-ovate, 2–5 × 1–2.5 cm, irregular-serrulate, acute, white-hispid abaxially and on adaxial veins, abaxial surface gray-green. Leaves reduced upwards. Umbels 10–15 cm across; peduncle 5–10 cm; bracts 7–9, oblanceolate to obovate, 3–6 × 0.5–2 cm, white-hispidulous along nerves on both sides, apex entire or 3–5-lobed, margin coarse-dentate; rays 10–15, 2–4 cm, densely hispidulous; bracteoles 5–9, lanceolate, 1–2 cm, similar to bracts; pedicels 10–15, 8–15 mm, hispidulous, elongating in fruit to 20 mm. Calyx teeth obsolete. Petals elliptic, white, ca. 1.5 mm. Stylopodium conic. Fruit oblong-ovoid, 7–10 × 1.8–2.5 mm; ribs all narrow-winged; vittae 1 in each furrow, 2 on commissure. Fl. Jul–Sep, fr. Aug–Oct.
This species is closely related to, and not always easy to distinguish from, P. benthamii. The presence of coarse, white hairs (reminiscent of those seen in Heracleum) on the leaf sheath and main veins is usually diagnostic, as is the gray-green underside of the leaves and the densely hispidulous rays and pedicels.
Open dwarf scrub, grasslands; 3000–3900 m. Xizang, NW Yunnan.