Juncus arcticus ssp. intermedius; The other subspecies of the Arctic Rush (see page on J. arcticus ssp arcticus). The inflorescences are usually lighter coloured (less black, more brownish). The defining difference though is the less-compactness of the flower bundles. This is the result of slightly longer stems below the flower bundles.. It can grow up to about 45 cm at most.
It is a member of the rush family (Juncaceae).