Japan Flora: leaf-blades 2-4 mm. wide; ligules 2-5 mm. long; panicles only slightly exserted, 10-25 cm. long; spikelets rather many, very short- pedicelled, 10-25 mm. long, 7- to 15-flowered; glumes nar­rowly ovate, the lower 1 mm., the upper about 2 mm. long; lemmas 2.5-3.5 mm. long.  Ponds and riverbanks.

Hok­kaido, Honshu.

var. infirma (Ohwi) Ohwi. Plant with larger lemmas, 4-5.5 mm. long. Occurs with the typial phase.