Stems freely branching proximally to distally, terete, 20–50(–70) cm. Leaves: length and width of those on main stem only slightly larger than those on branches; stipules with stipular sheaths inflated 3–5 times stem thickness, 2–9 cm, ligule absent, obscure, or to 0.2 mm; blade narrowly filiform to linear, 1–10(–15) cm × 0.2–2.9 mm, apex rounded, obtuse, or slightly notched; veins 1(–3). Inflorescences: peduncles terminal, erect, slender, 3–15 cm; spikes moniliform, 10–80 mm; verticels 3–12. Fruits brown, obliquely obovoid, 3–3.8 mm × 2–2.9 mm; beak inconspicuous. 2n = 78.
Phenology: Flowering late summer–fall.
Habitat: Deep lakes and ponds
Elevation: 0–2300 m
Alta., B.C., Man., N.W.T., Nunavut, Ont., Que., Sask., Yukon, Alaska, Colo., Idaho, Minn., Mont., N.Dak., Oreg., S.Dak., Utah, Wash., Wis., Wyo., Eurasia.
One hybrid, P. pectinatus × P. vaginatus (= P. × bottnicus Hagström), with this species as a putative parent has been described under the genus Potamogeton.