Juncus is a member of the rush family.   This variety is known as the corkscrew rush.  It is cool season, clump forming , and loves lots of moisture!  There is a large specimen at Thompson Rivers University in Kamloops.

Variety:

Juncus effusus 'Spiralis'     leaves are dark green, round, spiralling up and out from the crown, to 18" tall     flowers are brown, forming part way along the stem     zone 4     requires moist soil, good along waters' edge     also does very well in a pot partly submersed in a pond (do not let the crown be under water!)