Annual. Culms slender, creeping, branching and rooting at lower nodes, 8–15 cm tall. Leaf sheaths shorter than internodes, papillose-hispid, outer margin ciliate; leaf blades ovate-elliptic, thin, 0.8–1.5 × 0.3–0.6 cm, subglabrous or abaxial surface papillose-hispid, base rounded, margins not thickened, ciliate, apex acute; ligule almost absent. Panicle ovate in outline, 2–3.5 cm, eglandular, moderately branched; branches and pedicels slender, pedicels mostly longer than spikelets. Spikelets 1.7–1.8 mm, greenish or purplish green; florets clearly dissimilar; lower floret male, upper floret raised on distinct internode, bisexual; glumes subequaling or shorter than spikelet, elliptic-lanceolate, 5–7-veined, glabrous, apex obtuse; lower lemma herbaceous, elliptic-oblong, dorsally flattened, smooth, glabrous; anthers 1.3–1.5 mm; upper lemma crustaceous, strongly plano-convex, 1/2 length of lower floret, densely pubescent. Fl. and fr. Oct–Dec.

This species is very close to Isachne pulchella, but the whole plant is eglandular and has exceptionally small leaf blades and a small upper floret raised on a conspicuous internode. The anthers are also longer than in I. pulchella.

* Valleys, moist places; 300–500 m. Guangdong, Hainan.