香根草 xiang gen cao

Phalaris zizanioides Linnaeus, Mant. Pl. 2: 183. 1771; Vetiveria zizanioides (Linnaeus) Nash.

Tussocky perennial; roots stout, aromatic. Culms robust, 1–2.5 m tall, ca. 5 mm in diam. Leaf sheaths glabrous, lower sharply keeled and imbricate in fanlike clusters; leaf blades linear, pale green, stiff, 30–90 × 0.5–1 cm, pilose on adaxial surface toward base, otherwise glabrous; ligule a scarious rim. Panicle oblong in outline, 20–30 cm, usually contracted, purplish; branches numerous, lowermost 5–20 cm, bare at base, smooth or slightly scaberulous; racemes slender, with 5–13 spikelet pairs and a terminal triad; internodes and pedicels slightly scabrid. Sessile spikelet linear-lanceolate to almost linear, 4–5 mm; callus rounded, subglabrous; lower glume muricate, 3–5-veined, veins spinulosely aculeate, apex acute; upper glume spinulosely aculeate on keel, not awned; upper lemma slightly 2-toothed, awnless or mucronate; mucro 0–2 mm, not exserted. Pedicelled spikelet staminate, sparingly aculeolate or almost smooth. Fl. and fr. Aug–Oct. 2n = 20.

Commonly cultivated. Fujian, Guangdong, Hainan, Jiangsu, Sichuan, Taiwan, Yunnan (Xixhuangbanna), Zhejiang [native to India; cultivated elsewhere].

This species (Vetiver Grass) is said to have originated in India, but is now distributed throughout warm parts of the Old World and introduced into the S United States and West Indies. It has long been cultivated for the oil extracted from the aromatic roots, which is used in perfumery. More recently, its potential as a soil binder to prevent erosion has been recognized. It is planted in hedges for this purpose, particularly along the contours of sloping ground. The deep, non-invasive root system holds the plants firm, while the stiff, dense leaves trap soil and prevent it being washed away. It is also used as a forage grass.