Native of Eurasia and perhaps also coastal areas of North America; collected once as an introduction by O. A. Farwell in 1916 from River Rouge (Wayne Co.) This grows in moist, bare soil rather like the habitats of Juncus bufonius, but is often a plant of saline sites.

Though Farwell’s collection lacks habitat data, it may have been associated with the industrial sites so prevalent near the junction of the Rouge River and the Detroit River. The name Juncus ambiguus is sometimes misapplied to this plant.

This number was cited by Farwell when he published the new combination Juncus bufonius var. ranarius (Songeon & E. P. Perrier) Farw. (Farwell 1917a), but he provided no additonal information about its occurrence at River Rouge.