7. Pleurospermum nanum Franchet, Bull. Soc. Philom. Paris, sér. 8. 6: 140. 1894.
矮棱子芹 ai leng zi qin
Physospermopsis nana (Franchet) Pimenov & Kljuykov; Physospermopsis purpurascens (Franchet) Pimenov & Kljuykov; Trachydium purpurascens Franchet.
Small plants, 5–15 cm, glabrous. Stem reduced, slender, ribbed. Basal leaves petiolate; petioles 2–5 cm; sheaths broadly oblong-lanceolate, membranous-margined; blades ovate-oblong, 3–5 cm, 2–3-pinnate; pinnae 4–5 pairs, only the basal pinnules petiolulate; ultimate segments linear-lanceolate, 1–3 × 0.5–1 mm, entire or 3-toothed at apex. Stem leaves gradually reduced upwards, petioles short or wholly sheathing. Umbels 5–7 cm across; peduncles very short; bracts 5–7, leaf-like, 2–3 cm; rays 5–15, slightly unequal, 3–6 cm; bracteoles 6–10, oblong-ovate to broadly obovate, 1–2-pinnate, 6–10 × 4–8 mm, about equal to flowers, pale green, margin whitish in lower half; pedicels 15–20, 3–5 mm. Calyx teeth small, triangular-ovate, 0.15–0.3 mm. Petals white or purplish-red, obovate, ca. 1.2 mm. Anthers dark purple. Stylopodium short-conic. Fruit broad-ovoid, ca. 2.5 × 1.5 mm, sparsely pimpled; ribs prominent, narrowly sinuolate-winged, dark purple-black; vittae large, 1 per furrow, 2 on commissure. Fl. Jul–Sep, fr. Oct–Nov.
Dwarf Rhododendron scrub, marshy meadows; (2600–)3500–4600 m. SE Xizang, NW Yunnan.
This is an enigmatic species, rarely collected in fruit, and is here retained within Pleurospermum (on account of the white scarious margins of the bracts and bracteoles), but is possibly better placed in Physospermopsis. Some authors treat Physospermopsis purpurascens as a separate species, distinguished by the short or sometimes obsolete calyx teeth.