Juncus acuminatus Michx.
Family: Juncaceae
sharp-fruited rush, taper-tip rush, tufted rush
[Juncus acuminatus var. legitimus Michx.,  more...]
Juncus acuminatus image
from USDA Plants website  
Juncus acuminatus image
University of Wisconsin-Stevens Point, Robert W. Freckmann Herbarium (UWSP)  
Etymology: Juncus: the classical Latin name for the rush, possibly from jungere, "to join or bind," because the stems were used for binding
Plants: perennial rush
Conservation Status: Native