Bupleurum chaishoui Shan & M. L. Sheh

The multi-branched and thickened rootstock is used as the traditional Chinese medicine “chai shou” (柴首). The crude drug looks like a large head, hence the name “shou” (head).

Plants 0.5–1 m, perennial. Taproot gray-brown, stout, digitate-branched, capitate, woody when old forming a thickened caudex. Stems many, tufted, base without fibrous remnant sheaths. Basal leaves numerous, subsessile or shortly petiolate; blade oblanceolate, 4–6 × ca. 0.5 cm, dark gray-green, glabrous, nerves 7, margin white cartilaginous, apex obtuse. Cauline leaves lanceolate to elliptic, very unequal at the same node, 1.2–9 × 0.3–1.2 cm, 5-nerved, usually reflexed. Umbels numerous, small, terminal umbels 1–2(–4) cm across, lateral umbels less than 1 cm; bracts 2–4, linear, 0.6–7 × 0.3–1 mm, unequal; rays 3–5, 0.2–3 cm, slender when young, thickening with age; bracteoles 5, obovate or obovate-elliptic, 1.2–2.8 × 0.5–0.8 mm, equaling or exceeding the umbellules, nerves 3; umbellules ca. 5 mm across, 4–10-flowered; pedicels ca. 1 mm. Petals yellow. Stylopodium low-conic, yellow. Fruit ovoid-ellipsoid, brown, 3–3.5 × ca. 2 mm; ribs prominent; vittae 3 in each furrow, 4 on commissure. Fl. and fr. Aug–Oct.

NW Sichuan.

Among shrubs, sunny slopes; 2100–2700 m.