水牛草 shui niu cao

Pennisetum ciliare (Linnaeus) Link.

Perennial, tufted or shortly rhizomatous. Culms erect or ascending from a decumbent or stoloniferous base, slender to moderately stout, sometimes much branched, up to 1 m tall. Leaf sheaths glabrous or pubescent; leaf blades linear, green or grayish, 10–50 × 0.4–0.8 cm, with scattered, tubercle-based hairs; ligule 0.5–3 mm. Inflorescence 3–15 cm, densely bristly, burrs contiguous, rachis puberulous. Burrs composed of many bristles; bristles antrorsely barbed; inner bristles 7–14 mm (one stouter and slightly longer), connate at extreme base to form a shallow disc 0.5–1.5 mm wide, somewhat flattened around spikelets, grooved on outer face, ciliate on inner margins, tips extended into flexuous bristles clearly exceeding spikelets; outer bristles numerous, shorter, slender. Spikelets 1–4 in burr, 3–5 mm; lower glume 1/3–1/2 spikelet length; upper glume ca. 1/2 spikelet length. 2n = 36.

Pastures and weedy places, introduced. Taiwan [native to India, Pakistan; Africa, SW Asia; introduced in America and Australia].

This is a polymorphic species occurring naturally from Africa to India. Some superior strains have been selected and distributed in warm parts of the world for pasture and fodder in dry areas (Buffel Grass), and the grass has become a widespread weed. It was introduced to Taiwan as a pasture grass, and is now naturalized in the south of that island.

Cenchrus ciliaris may easily be mistaken for a species of Penni-setum, as the basal fusion of the bristles is rather slight. However, the flattening and grooving of the bristles around the spikelets is a characteristic feature of Cenchrus and is not found in Pennisetum.