Lewis & Short

sĭser, ĕris, n. (masc. in plur. siseres, Plin. 20, 5, 17, § 35) [σίσαρον], a plant with an esculent root, skirwort or skirret: Sium sisarum, Linn.; Plin. 19, 5, 28, § 90; 20, 5, 17, § 35; Col. 11, 3, 18; 11, 3, 35; 12, 58, 3; 10, 114.