Potamogeton paramoanus sp. nov. from the p'aramo of the northern Andes is most similar to P. epihydrus. Potamogeton paramoanus Haynes & Holm-Nielsen, sp. nov., fig. 1 TYPE: Ecuador, Carchi, Paramo El Angel, in the pass on road El Angel-Tulcan, 78?54'W, 0041'N, very humid Espeletia-pairamo, in stream, 3450-3550 m, 15 May 1973, L. Holm-Nielsen, S. Jeppesen, B. L,6jtnant, andB. 0llgaard 5513 (holotype: AAU!; isotypes: QCA, UNA). Plantae perennes, herbaceae, crescentes submersae aquis dulcibus. Folia disticha, submersa vel natantia; folia submersa alterna, sessilia, habentia 4-6 series lacunarum in utroque latere costae; folia natantia subopposita, petiolata, petiolis vulgo complanatis. Inflorescentiae terminales vel in axillis foliorum et submersorum et natantium. Fructus circa 2.5 mm longus, circa 2.1 mm latus, praebens unam dorsalem alam et duas laterales carinas. Perennial, glabrous, herbaceous plants growing submersed in fresh waters, propagating by seeds and rhizomes. Stems varying in length with water depth, 19-75 cm long, 1-2 mm wide, terete to slightly compressed, rooting at lower nodes, the nodes without oil glands. Leaves mostly both submersed and floating, rarely only submersed; submersed leaves alternate, distichous, sessile, entire, pellucid, linear, 3.5-26.5 cm long, 1-4.1 mm wide, 3-7-veined, with 4-6 rows of lacunae each side of midrib, the apex acute to round obtuse; floating leaves subopposite, distichous, petiolate, the petioles flattened or occasionally terete, 14-44 mm long, 0.54.0 mm wide, the blade entire, coriaceous, elliptic to oblong-elliptic, 1431 mm long, 6-9 mm wide, 5-9-veined, the base gradually tapering into the petiole, the apex acute to round obtuse; stipules fibrous, inflated to rarely closely enclosing stem, tubular, convolute, free from the leaves, 5-26 mm long, 2-5 mm wide. Turions absent. Inflorescences terminal and in axils of both submersed and floating leaves, submersed and emersed, cylindrical spikes with 6-8 whorls of 2-4 flowers each, 6-14 mm long, 3-5 mm diam.; peduncle cylindric, slightly arched outward, 11-27 mm long, 0.4-1.1 mm diam. Flowers with rounded, short-clawed perianth segments 1.6-1.8 mm wide, the claw ca. 0.5 mm long; anthers 0.7-1 mm long. Fruit dorsally winged, ca. 2.5 mm long, ca. 2.1 mm wide, with a prominent beak 0.5 mm long, the sides plump, each with one lateral keel.