大米草 da mi cao

Spartina townsendii H. Groves & J. Groves var. anglica (C. E. Hubbard) Lambinon & Maquet.

Perennial with soft fleshy rhizomes, deeply rooted. Culms forming large clumps, erect, 10–50(–120) cm tall, 3–35 mm in diam. Leaf sheaths mostly longer than internodes, smooth; leaf blades linear, flat or inrolled upward, 10–45 × 0.7–1.5 cm, smooth, apex fine, hard, upper blades usually patent; ligule 2–3 mm. Racemes racemosely arranged, 2–6(–12), 7–23 cm, stiff, erect or slightly spreading; spikelets closely overlapping; rachis terminating in a hard bristle up to 5 cm. Spikelets 12–21 mm, pubescent; lower glume 2/3–4/5 as long as spikelet, acute; upper glume lanceolate-oblong, as long as spikelet, acute; lemma lanceolate-oblong, ca. 1 cm, keel scaberulous, pubescent, entirely or in upper half; palea slightly longer than lemma. Anthers 7–13 mm. 2n = 124.

Tidal mudflats of coast, introduced. Jiangsu, Zhejiang [native to England].

Spartina anglica is an extremely vigorous species, which arose in England at the end of the 19th century by the natural hybridization of S. alterniflora and S. maritima (Curtis) Fernald, followed by a doubling of chromosomes in the resulting sterile hybrid to form a fertile amphidiploid. It was introduced from England to China in 1963 and was planted in coastal areas. At first it spread rapidly, occurring in all coastal provinces by 1985. In recent years it has died back, leaving only small residual colonies. The reasons for the dieback are not fully understood.