4. Themeda helferi Munro ex Hackel in A. Candolle & C. Candolle, Monogr. Phan. 6: 665. 1889.
无茎菅 wu jing jian
Themeda acaulis B. S. Sun & S. Wang; T. ciliata (Linnaeus f.) Hackel subsp. helferi (Munro ex Hackel) A. Camus; T. quadrivalvis (Linnaeus) Kuntze var. helferi (Munro ex Hackel) Bor.
Annual. Culms very slender, solitary or in small loose tufts, up to 30 cm tall. Leaf sheaths shorter than internodes, glabrous; leaf blades flat or folded, 5–10 × 0.2–0.4 cm, a few tubercle-based bristles on lower margins, otherwise glabrous, acute; ligule ca. 1 mm, truncate, ciliolate. Spathate fascicles arising from all leaf axils from base to apex of culm, fascicles congregated on slender 1–3-noded branches; spathes and spatheoles narrowly lanceolate-caudate, glabrous, innermost ca. 2 cm. Raceme composed of a triad of 1 sessile and 2 pedicelled spikelets above the involucre of 2 homogamous pairs. Homogamous spikelets all sessile, arising at same level, male with both glumes present, 4–5 mm, narrowly lanceolate, stiffly setose in upper half with ca. 3 mm, tubercle-based bristles, upper keels scabrid. Sessile spikelet ca. 4 mm; callus 0.5–1 mm, obtuse, brown bearded; lower glume dorsally slightly flattened, pubescent throughout; awn 3.5–4.5 cm. Pedicelled spikelet 5–6 mm, barren.
Stream banks; ca. 600 m. Yunnan (Longling, Zhenkang) [Myanmar (Tenasserim)].
This slender, annual species is remarkable in that fascicles of racemes are borne all the way down to the base of the plant, so that the whole culm in effect forms the compound inflorescence. It appears to be rare and fairly localized in its distribution.