Leaves all submersed, sessile, linear-oblong, 2-5 mm wide, flat, with numerous fine longitudinal nerves; stipules free, disintegrating into fibres. Spike to 1.5 cm long, dense. Achenes flattened with ± 3-ridged keel, beak well-developed, curved.

Rhizome short with close fibrous stipules and roots. Branches erect, at first simple with long lvs, ∞ short lfy branchlets produced in lf-axils in spring and elongating in autumn, sts rooting from nodes. Stipules to 2 cm. long, free, open, obtuse, with many close nerves that persist as fibres at older nodes. Lvs all submersed, sessile; lamina 1.5–10 cm. × 2–5 mm., entire, linear-oblong, obtuse to slightly emarginate, only slightly narrowed to base, membr., longitudinal nerves ∞, fine and close, one in each half us. stronger. Peduncles from axils of upper lvs, 2–4 cm. long, simple, slender. Spike to 1.5 cm. long, dense. Achene c. 3 × 2.5 mm., flattened on sides, keel ± 3-ridged, beak rather well-developed, curved.