Isachne kunthiana (Wight & Arn. ex Steud.) Miq.

This species is very close to Isachne schmidtii Hackel, from Indonesia and peninsular Malaysia, which is somewhat smaller, with shorter leaf blades, a more contracted panicle, and especially differs in its glumes extending beyond the florets. Isachne schmidtii has often been confused in the literature with I. kunthiana (Wight & Arnott ex Steudel) Miquel, from India and Sri Lanka, which also has glumes longer than the florets, but differs by its underground rhizomes and glabrous or setose glumes.

Locally this species is found in moist ground at low elevations along forest margins.

Slender trailing herb, annual or short-lived perennial. Culms stoloniferous with 1 or 2 wiry roots from lower nodes, flowering branches up to 25 cm tall, nodes pubescent. Leaf sheaths glabrous or hispid, outer margin ciliate becoming setose near ligule; leaf blades lanceolate, 5–7 × 1–1.8 cm, abaxial surface glabrous or papillose-hispid, adaxial surface glabrous or thinly pilose, base obtuse to rounded, apex acuminate; ligule 1–2 mm. Panicle elliptic to ovate in outline, 3–5.5 cm, eglandular; branches ascending to spreading, branches and pedicels stout, smooth, lateral pedicels shorter than spikelets. Spikelets broadly elliptic, 2.1–2.4 mm, green; florets similar; glumes equal to spikelet or upper slightly shorter, lower glume narrower, 7–9-veined, upper 9–11-veined, densely scabrid-hispidulous, spicules longer toward apex; lemmas pale, ovate to subrotund, weakly convex, leathery, smooth, pubescent on the inrolled margins toward apex; palea of upper floret puberulous. Fl. and fr. Oct–Dec.

Culm long creeping, flowering branches 10-20 cm tall. Blade lanceolate to ovate-lanceolate, 1.5-3 cm long by 7-9 mm wide, base cordate, margins prominently thickened; sheath margins ciliate, slightly shorter than the internode; ligule a ring of hairs, about 1.5 mm long. Panicle 3-4 cm long, stout; pedicel clavate at the apex. Spikelets elliptical, grayish-green, obtuse, 2-2.3 mm long; glumes similar, rigid-hispid, ovate, exceeding the floret, subequal; lower glume slightly longer, convexed, 9-11-nerved, nerves scabrous. Florets similar, ovate or elliptical, obtuse, 1/4 to 1/3 as long as the glumes, glabrous or the lemmas slightly hispid on the inrolled margins; anther about 1 mm long.

Distributed in swampy grounds in mountain regions in South India, Ceylon and Southeast Asia generally.

Moist places in forests. Fujian, Guangdong, Guangxi, Hainan, Taiwan [Japan (S Ryukyu Islands)].

Isachne kunthiana (Wight & Arnott ex Steudel) Miquel subsp. nudiglumis (Hackel) T. Koyama; I. kunthiana var. nudi-glumis (Hackel) T. Koyama; I. myosotis Nees var. nudiglumis Hackel.

Isachne firma sensu Hayata, l. c. 7: 57. 1918; Honda, l. c. 279. 1930.
Isachne schmidii Hack., Bot. Tidsskrift 24: 97. 1901; Ohwi, Fl. Jap. 151. 1956.
Isachne commelinifolia Warb., Ohwi, l. c. 11: 55. 1942.