Potamogeton illinoensis Morong

• Authority

  Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.

• Family

  Potamogetonaceae

• Scientific Name

  Potamogeton illinoensis Morong

• Description

  Species Description - Stem stout, usually much branched, to 2 m; submersed lvs lanceolate to oblanceolate or narrowly obovate, 8–20 × 2–5 cm, 9–19-nerved, acute, tapering to a sessile or short-petioled base; floating lvs not always developed, lanceolate to elliptic, 7–13 × 2–6 cm, the stout petiole 4–11 cm; stipules axillary, free, obtuse, 4–10 cm; peduncles 4–12 cm, usually thicker than the stem, but not clavate; spikes dense, cylindric, 2.5–6 cm; frs broadly semi-obovoid, 3–4 mm (including the 0.5 mm beak), with 3 conspicuous but low dorsal keels; 2n=104. In quiet water; N.S. to Ont., Minn., and Calif., s. to Fla. and Mex. (P. angustifolius; P. lucens, misapplied)

• Common Names

  Illinois-pondweed