马尾柴胡 ma wei chai hu

Plants 50–100 cm, biennial. Taproot yellowish-brown, elongate-terete, unbranched. Stem solitary, several-branched above, slender, base purplish-tinged, without fibrous remnant sheaths. Basal leaves numerous, narrowly linear, 16–30 × 0.25–1 cm, thin-papery, abaxially slightly glaucous, 5-nerved, base tapering into petiole, margin white scarious. Cauline leaves shorter, sessile, somewhat clasping. Umbels numerous, 1.2–3 cm across; peduncles and rays very slender; bracts 3–5, very small, 0.2–2 × 0.1–0.4 mm, lanceolate or squamose; rays (3–) 4–6(–9), 7–50 mm, unequal; bracteoles 5, elliptic or spatulate, 1.5–2.5 × 0.5–1 mm, mostly shorter than umbellules in fruit; umbellules 2.5–5 mm across, 6–12-flowered; pedicels 1–1.5 mm. Petals yellow, midvein dark. Stylopodium low-conic, yellow. Fruit ovoid, brown, 2.6–3 × 2–2.2 mm, glaucous, base rounded; ribs inconspicuous; mericarps pentagonal in cross section; vittae 3 in each furrow, 4 on commissure. Fl. Jul–Aug, fr. Aug–Oct.

Among shrubs, open slopes, roadsides; 1400–3200 m. S Gansu, W Sichuan, SE Xizang.

This species is used as a regional substitute for the Chinese Medicine “chai hu.” It is similar to Bupleurum malconense but differs in the unbranched rootstock and the narrow, longer leaf blades.