Leersia oryzoides (L.) Sw.
rice cutgrass
Rhizomatous, yellow-green erect perennials. Leaf-sheath rounded, retrorsely scabrid between the fine nerves. Ligule c. 1 mm, chartaceous, truncate, or erose. Leaf-blade 9-20 cm × 7-10 mm, flat, finely prickle-toothed on both surfaces and on margins, finely pointed. Culm to 50 cm, internodes glabrous; nodes pubescent. Panicle 10-14 cm, enclosed at base by uppermost leaf-sheaths; branches filiform, flexuous, naked in lower ⅓. Spikelets c. 5 mm, elliptic-oblong, very pale green to later dark brown, shortly pedicelled, falling entire at maturity. Glumes reduced to a minute cupule at tip of pedicel. Lemma c. 5 mm, cymbiform, nerves 5, confluent at apex, firmly membranous, stiffly toothed on strong keel and scattered elsewhere, abruptly narrowed above to a short, blunt tip. Palea ≈ lemma, texture similar, hyaline, 3-nerved, keel stiffly long toothed. Stamens 3, sometimes 2; anthers c. 1.5 mm, 0.5 mm in cleistogamous flowers. Gynoecium: ovary glabrous; stigmas plumose, laterally inserted. Caryopsis c. 3 × 1.2 mm, laterally compressed, whitish to dark brown; embryo small; hilum linear, ≈ caryopsis.
N.: South Auckland (along Waikato R. and on margins of Lakes Waipapa, Arapuni, and Karapiro). Damp ground.
Naturalised from North America and Europe.
In all specimens seen the panicles had emerged from the leaf-sheaths and spikelets were chasmogamous. Cleistogamous spikelets with anthers 0.4-0.7 mm, in panicles enclosed by the leaf-sheaths, occur in CHR 467467 P. J. de Lange Waikato River, Mar 1990.
