Eriophorum vaginatum L. (hare's-tail cottongrass, tussock cottongrass, sheathed cottonsedge) is a species of perennial herbaceous flowering plant in the sedge family Cyperaceae. It is native to bogs and other acidic wetlands throughout the Holarctic Kingdom. It is a 30–60 cm high tussock-forming plant with erect solitary spikelets.