Juncus effusus / Common Rush

Common rush is indeed common - it has a nearly cosmopolitan distribution, found in swamps in most temperate regions of the world. The dark green leaves resemble grasses, and the flowers are minute but ripen to a tan green that is attractive when grown en masse. Grows 2 to 4 feet tall and requires full sun with constant moisture.

For more information see below:

https://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?kempercode=c262