Japan Flora: Larger; culms 30-50 cm. long; leaf-blades 10-15 cm. long, 4-6 mm. wide; panicles exserted, 10-20 cm. long, 3-5 cm. wide, the branches subverticillate, ascending, slender, scabrous; spikelets 6-9 mm. long, green, 7- to 9-flowered, the pedicels appressed to the branchlets; glumes 1-nerved, oblong, obtuse, about 1.5 to 2 mm. long; lemmas about 3.5 mm. long, ovate, 7-nerved, scaberulous. June-July. Ponds.