United States, Minnesota, Cook, Boundary Waters Canoe Area Wilderness, Rugged bedrock terrain northwest of Brule Lake, 24 miles northwest of Grand Marais. T63N R3W NE1/4 of SW1/4 Sec. 5
Locally common in broad mud flats in the western end of the narrow, bedrock-entrenched basin that encompasses Cuckoo Lake. Co-dominant with Juncus brevicaudatus in the subtly higher, drier zone bordering the upland. Deep moist muck (and moist organic silt amongst small boulders on the upland margin). Full sun.