Isachne nipponensis Ohwi

This grass grows at low elevations in different localities. It likes shade and gregariously in half shade forests.

Isachne nipponensis is very close to I. myosotis, but has a rather looser growth, larger leaves and spikelets, and a broader, very open panicle with slender, scaberulous branches.

Isachne nipponensis var. kiangsiensis P. C. Keng (Acta Phytotax. Sin. 10: 21. 1965), described from Jiangxi, has smooth, glandular panicle branches and pedicels and may represent a different species.

Culm branching, long creeping and forming mats, nodes pubescent, the flowering culm 5-10 cm tall. Blade ovate-lanceolate, 15-20 mm long by 4-8 mm wide, base truncate; densely pubescent to papillose-pilose on both surfaces, marginsthickened; ligule a ring of hairs, about 1 mm long; sheath ciliate non margins, 1/3 as long as the internode. Panicle few-flowered, 3-5 cm long. Spikelets green, about 1.5 mm long, broadly elliptical or subglobose when mature; glumes similar, 3-7-nerved, about equaling the spikelet, obtuse, usually with a few stiff hairs toward the apex. Florets similar in appearance, 1.2-1.3 mm long, more or less pubescent.

Low herb forming loose mats. Culms slender, creeping, rooting and branching at nodes, flowering branches up to 15 cm tall. Leaf sheaths thinly pubescent, outer margin ciliate; leaf blades lanceolate-ovate, thin, 2–3.5 × 0.5–0.9 cm, abaxial surface glabrous or pilose, adaxial surface hispid with long scattered hairs, margins white, finely scabrid, base obtuse, apex shortly acuminate; ligule ca. 1 mm. Panicle broadly ovate in outline, 2–8 cm, eglandular, rather sparsely branched, spikelets 10–50; branches and pedicels widely spreading, very slender, scaberulous. Spikelets broadly elliptic, (1.3–)1.5–1.8 mm, green infrequently tinged purplish; florets similar; glumes equal to spikelet or lower slightly shorter, ovate-elliptic, shortly hispid above the middle, often with a few stout, sometimes overtopping bristles, apex obtuse, lower glume 3–5-veined, upper glume 5–7-veined; lemmas broadly elliptic, leathery, thinly pubescent near margins and apex. Fl. and fr. summer to autumn. 2n = 40.

Distributed in Southern Japan, China and Taiwan.

Fujian, Guangdong, Guangxi, Guizhou, Hunan, Jiangxi, Sichuan, Taiwan, Zhejiang [Japan, Korea (Cheju Island)].

Wet shady places; below 1000 m.

Isachne myosotis Honda, l. c. 281. 1930.
Isachne myosotis var. minor Honda in Bot. Mag. Tokyo 38: 58. 1924, Monogr. 281. 1930.