Schlüggell
And depending on your bioregion - It can be used as the drill for a Fire Drill & but as always for this you must carefully choose the wood for the base.
Native Americans actually had special cultivars for an edible tuber and polen for the starch.
It also used by the Ainu of NorthEastern Asia for part of the wall construction for their homes. They use 2 panels of Great Reedmace mats infilled with 3-4" of down for insulation akin to a "Wall Sandwich"....