双稃草 shuang fu cao

Festuca fusca Linnaeus, Syst. Nat., ed. 10, 2: 876. 1759; Diplachne fusca (Linnaeus) P. Beauvois ex Roemer & Schultes; D. malabarica (Linnaeus) Merrill, nom. rej.; Leptochloa mala-barica (Linnaeus) Veldkamp, nom. rej.; Poa malabarica Linnaeus, nom. rej.

Perennial, loosely tufted to rhizomatous. Culms erect or geniculate and rooting from lower nodes, up to 100 cm or more tall. Leaf sheaths glabrous; leaf blades tough, usually involute, 5–30(–50) × 0.15–0.3(–0.6) cm, adaxial surface scabrid, abaxial surface subglabrous; ligule 3–12 mm, acute. Inflorescence 15–25 cm, scabrid; racemes 3–28, indistinctly unilateral, 4–20 cm, straight, ascending or spreading, spikelets usually distant. Spikelets glaucous-green, subterete, 6–14 mm, florets 5–12; glumes keeled; lower glume lanceolate, 2–3 mm, acute; upper glume narrowly oblong, 3–4 mm, acute or mucronate; lemmas narrowly oblong, dorsally subrounded, lowest 4–5 mm, lower lateral veins pilose, entire or 2-dentate, midvein often produced into a short 0.3–1.6 mm awn; palea ciliolate along upper keels. Callus laterally pilose. Anthers 0.5–0.75(–2.5) mm. Caryopsis elliptic-oblong, 1.5–2.5 mm, dorso-ventrally flattened. Fl. and fr. Jun–Sep. 2n = 20.

Shallow water, marshy, sometimes brackish ground. Anhui, Fujian, Guangdong, Hainan, Hebei, Henan, Hubei, Jiangsu, Liaoning, Shandong, Taiwan, Yunnan, Zhejiang [India, Indonesia, Malaysia, Myanmar, Pakistan, Philippines, Sri Lanka, Thailand; Africa, SW Asia, Australia].

This is a widespread, polymorphic species varying in habit, height, and robustness of the culm, compactness of the inflorescence, and in the lemma tip. It is a salt-tolerant species and is known to excrete salt through glands on the leaves.