A medium to large species, S. majus occurs as scattered plants or in small patches, emergent or semi-submerged. Capitula are olive or khaki, with a clearly visible terminal bud. All branches in a fascicle are similar in appearance, only varying in length. Branch leaves are about 5 times as long as wide, and only slightly longer relative to width at the branch tip. Leaves are straight along the proximal half of branches, becoming more curved towards the branch tip and are not in straight lines. Stem leaves are rounded-triangular, 1.5-2 times as long as wide, usually concave, pendent-spreading or spreading. Capsules are very rare.