Potamogeton richardsonii (A.Benn.) Rydb.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Species Description - Much like no. 29 [Potamogeton perfoliatus L.]; lvs narrower, lance-ovate to nearly linear, (3–)5–12 cm × 5–20 mm, acute, sessile and cordate-clasping, (3–)13–21(–35)-veined, 3(5) veins stronger; stipules 1–2 cm, soon disintegrating into ± persistent white fibers; peduncles 1.5–25 cm; spikes 1.5–3 cm; frs 2.2–4.2 mm; 2n=52. Ponds and streams; Que. to Alas., s. to Pa., Ind., Io., Colo., and Calif.