This video from Florida in the USA says about itself:
How to identify Soft rush, Juncus effusus
26 September 2013
Translated from Dutch FLORON botanists:
Sunday, August 17, 2014
During a FLORON weekend in the Westerwolde region inventory leafy rushes, with a reputation as very rare plants, were found in not less than five square kilometre research grids. They are the first sites for this species ever discovered in Groningen province. Possibly leafy rush, a relative of the very commonly occurring toad rush, has been overlooked and it may occur in more places in the Netherlands.