Elodea canadensis Michx.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Species Description - Lower lvs small, opposite, ovate or lance-ovate, the others ternate, 6–17 × 1–5 (avg 2) mm, linear to lance-oblong, bright green, ± firm, the upper closely imbricate; fls elevated on a very slender, pedicel-like hypanthium 2–30 cm; staminate spathes 7–10+ mm (including the slender base), expanded and 2-lobed above; pistillate spathes 8–20 mm, cylindric; sep of staminate fls 3–4 mm, of pistillate fls 2–3.5 mm; pet white, clawed, 2–4.5 mm; fr turbinate, 5–6.5 mm with a 5–6 mm beak; 2n=48. In quiet water, Que. to B.C., s. to N.C., Ala., Ark., and Calif. July–Sept. (Anacharis c.; Philotria c.)