Carex aquatilis Wahlenb. (water sedge)
Hurd, E.G., N.L. Shaw, J. Mastrogiuseppe, L.C. Smithman, and S. Goodrich. 1998. Field guide to Intermountain sedges. General Technical Report RMS-GTR-10. USDA Forest Service, RMRS, Ogden. Courtesy of USDA FS RMRS Boise Aquatic Sciences Lab.
<a rel="nofollow" class="external text" href="https://plants.usda.gov/gallery/pubs/caaq_004_pvp.jpg">USDA-NRCS PLANTS Database / 1998. Field guide to Intermountain sedges. General Technical Report RMS-GTR-10. USDA Forest Service, RMRS, Ogden.</a>