Description from Flora of China
Perennial. Culms tufted, slender, erect or geniculately ascending but not rooting from lower nodes, 14–18 cm tall, nodes inconspicuous, glabrous. Leaf sheaths loose, compressed, keeled, longer than internodes; leaf blades narrowly linear, 1–6 × 0.1–0.2 cm, glabrous; ligule ca. 0.5 mm. Racemes solitary or several per node, 5–10 cm, articulation line oblique, not disarticulating. Sessile spikelet longer than adjacent internode, or lower ones shorter, 3–7.5 mm; callus obscure; lower glume lanceolate, papery, flat on back, smooth, evenly tapering to an acuminate or shortly caudate, sometimes minutely emarginate apex; upper glume adnate to rachis, 4–7.5 mm, long acuminate; lower floret 2–3 mm; upper floret 1.7–2.8 mm; anthers 0.7–0.8 mm. Pedicelled spikelet 7–12 mm, lower glume scabrid on upper edges, long-acuminate, upper glume caudate-aristate. Fl. May.
This species is known only from the type gathering. It has been included in Hemarthria vaginata, but H. humilis is a more slender plant and, besides the key characters, also differs in its inconspicuous culm nodes, shorter lemmas, and shorter anthers.
* Open marshes. Guangdong.