Eleocharis microstachya Britt.

Oregon: Umatilla County: South shore of Columbia River reservoir, Lake Umatilla, north of Interstate 84, 15.2 air kilometers east of northeast tip of Big Blalock Island. Elev. 80 m.
45.9127° N, 119.415° W
Coordinate Source: Specimen Label.
Gently sloped sand and mud shoreline, full sun, over basalt, with Xanthium strumarium, Bidens frondosa, Cyperus strigosus, Salix exigua. Rhizomatous perennial, common.

Peter F. Zika 29105, Aug 20, 2017
WTU, Accession: 416480, Barcode: WTU-V-035367