Potamogeton diversifolius Raf.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Species Description - Stems slender, to 15 dm, clustered, sparsely branched above the base; submersed lvs linear to filiform, 1–10 cm × 0.1–0.5 mm, obtuse to more often acute or even setaceous-tipped, 1(3)-veined, the larger ones with narrow lacunar bands flanking the midvein; stipular sheaths membranous, 2–18 mm, the adnate part mostly shorter than the free tip; floating lvs (not always produced) lance-elliptic to suborbicular, acute to rounded at each end, 5–40 × 2–20 mm, the 3–17 veins strongly impressed beneath, their stipular sheath free from the 5–40 mm petiole; fruiting spikes dimorphic, those axillary to submersed lvs globular to ellipsoid, with 1–15 frs, on ± recurved, slightly clavate peduncles 1–10 mm, those axillary to floating lvs more cylindric, sometimes to 3 cm, with 5–120 frs, on peduncles 3–32 mm; frs compressed, ± orbicular, 1–2 mm, with a minute beak, the entire or toothed dorsal keel usually flanked by a pair of lateral keels that may be represented only by a row of teeth; embryo snail-coiled. Shallow water; Me. to Mont. and Oreg., s. to Fla. and Mex. Two fairly well marked vars.