Abstract The major lipids isolated in a phytochemical study of Sonchus arvensis were 1, 2- dilinolenyl-3-O-β-d-galactopyranosyl-sn-glycerol, 1, 2-dilinolenyl-3-O-(α-d-galactopyranosyl- (1→ 6)-O-β-d-galactopyranosyl-sn-glycerol and the previously undescribed 1-linolenyl-3-O- β-d-galactopyranosyl-sn-glycerol.