Najas flexilis (Willd.) Rostk. & W.L.E.Schmidt
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Species Description - Monoecious; stems 0.5–5 dm, 0.2–0.6 mm thick, often profusely branched above; lvs 1–4 cm × 0.2–0.6 mm, spreading or ascending, with sloping shoulders at the base and tapering above to a long, slender point, minutely serrulate with 35–80 unicellular teeth per side; anthers monothecal and with a single microsporangium; seeds (1.2–) 2.5–3.7 mm, smooth and glossy, yellow to deep brown, ± obovate, widest above the middle, very lightly areolate in ca 30–50 rows. In lakes and rivers; Nf. to B.C., s. to Va., W.Va., O., Ind., Io., Nebr., and Utah.