Description from Flora of China
Hymenidium macrochlaenum (K. T. Fu & Y. C. Ho) Pimenov & Kljuykov.
Plants 40–60 cm. Root stout conic. Stem ribbed and branched. Basal and lower petioles 4–6 cm, flattened, membranous-winged, sheaths broad, oblong, membranous; blades broadly triangular-ovate, tripartite; median lobes ovate, 1.5–3 × ca. 1.5 cm, larger than narrowly ovate lateral lobes, serrate. Leaves reduced upwards, with petioles becoming wholly sheathing. Umbels ca. 10 cm across; bracts 7–10, oblanceolate, 3–5 × ca. 1 cm, pilose along veins, apex 3–5-lobed; rays 10–25, 5–6 cm; bracteoles 6–8, elliptic-obovate, 1–1.5 × 0.3–0.5 cm, apex 3–5-lobed, median stripe green, margins white; pedicels numerous, ca. 8 mm. Calyx teeth obsolete. Petals broad-ovate or rounded, pinkish. Stylopodium short-conic. Immature fruit ellipsoid; ribs all broadly sinuolate-winged; vittae 1 in each furrow, 2 on commissure (mature fruit not known). Fl. Jun–Jul.
This incompletely known taxon is recorded only from the type gatherings. It is closely allied to P. benthamii.
Grassy slopes in mountains; ca. 3500 m. SW Xizang.