Perennials. Culms to 1 m tall, robust, 3-angled, scabrous, glabrous. Leaf sheath 7-25 cm, to 2 mm thick, leathery to ± fleshy, glabrous, sometimes 3-winged, basal ones purplish red; contraligule not prominent; leaf blade linear, ca. 1 m × 1-2.5 cm, glabrous, margins sometimes scabrous, apex acute. Involucral bracts setaceous, basalmost to 1.5 cm; bractlets glumelike, shorter than spikelets. Inflorescences compound paniculate, ca. 15 × 7-8 cm, with many branches; branch axes long, angled, scabrous, with many spikelets. Spikelets 1 or 2 in a cluster, dark brown, unisexual. Male spikelets many, more than female ones, oblong-ovoid, ca. 4 mm, apex truncate; glumes 2-3 mm, membranous, with rust-colored lines. Female spikelets usually at base of branch, narrowly ovoid, slightly longer than male ones, apex acuminate; glumes triangular-ovate, ovate-lanceolate, or broadly ovate, slightly longer than male glumes. Male flowers: stamen 1; anther linear, ca. 1.7 mm; connective apex protruding, 1/5-1/4 as long as anthers. Female flowers: stigmas 3. Disk brown, triangular-cordate, ca. 1.5 mm in diam., 3-lobed; lobes triangular, short, margin reflexed, apex acute. Nutlet white or gray, ovoid, ca. 3 × 2.5 mm, bluntly triangular, smooth, shiny, glabrous. Fl. and fr. Apr.
Perennial, stout, aquatic, with evergreen aerial parts. This species is unlikely to be confused with any other. It is very robust, forms dense, almost pure stands in shallow coastal pans, has leaves which are broader and thicker than those of any other local species and is the only southern African species other than S. lacustris with a very small hypogynium with three obtusely triangular lobes. The two species are allopatric and differ in habit.
Perennial. Rhizome elongate, 5-17 mm thick; scales brown. Culms 1.3-1.8(-2) m tall, glabrous. Leaves mostly crowded towards base of culm, 20-40 mm broad, bases sometimes corky, up to 5 mm thick, glabrous; sheaths usually split almost to the base from concave mouths. Inflorescence a single terminal panicle without (very rarely with) foliaceous bract, 100-200 x 50-120 mm. Male spikelets sessile, 3.5-4.5 mm long; glumes reddish-brown, glabrous or hispidulous. Female glumes similar, 3.5-5 mm long. Achene broadly ovoid to subglobose, 1-3.5 x 2.5-2.8 mm, glabrous, smooth, grey-brown; hypogynium small, trilobed, lobes short, broadly triangular, white or finely red-brown striate.