A type of chives, which is similar to regular chives, but has a stronger flavor. There are four main varieties of nira grass: green nira grass which is dark green in color and has a distinct pungent taste; yellow nira grass which is pale yellow in color and has a mild onion flavor; gau choy fa which has rounded stems that have a small flower bud at the tip; gau choy sum which resembles gau choy fa in visual appearance but has its own distinct flavor.