Shamgrass is a perennial herbaceous plant of the genus Shamgrass in the family Cyperaceae. The rhizome is slender and grows prostrately, with enlarged spindle shaped tubers at the tip; The leaf cluster grows at the base of the stem, and the leaf sheath is closed and wrapped around the stem. The leaves are narrow and linear, shorter than the scale, and the sheath is brown; The inflorescence is compound spike shaped, with broad white transparent wings on the spikelet axis; Scales arranged in a tile like pattern, ovate or oblong ovate, green in the middle, purple red or reddish brown on both sides, long style; Small nuts are oblong ovate and triangular in shape; The flowering period is from May to August; The fruiting period is from July to November. The root and stem of sedge grow continuously and are long, resembling a small water chestnut, hence the name 'pig water chestnut'.