Broad Leaved Pondweed

Foodplant / feeds on
Bagous limosus feeds on Potamogeton natans

Foodplant / miner
larva of Cricotopus brevipalpis mines live leaf of Potamogeton natans
Remarks: season: summer
Other: sole host/prey

In Great Britain and/or Ireland:
Foodplant / spot causer
sorus of Doassansiopsis hydrophila causes spots on floating leaf of Potamogeton natans

Foodplant / open feeder
adult of Donacia versicolorea grazes on leaf of Potamogeton natans
Remarks: season: (5-)7-8(-10)

A rare species, confined to the temperate Himalayan regions of our area.

Potamogeton natans is the common floating-leaved pondweed of the north temperate ure areas. It is essentially circumboreal and can easily be identified by floating leaves that are almost always cordate at the base of the blade, the petiole with a short band of light tissue at its apex, and the submersed phyllodial leaves. Also, the apex of the petiole usually is bent so that the blade appears oriented in the opposite direction from which the petiole appears to be oriented.

One hybrid, Potamogeton natans ´ P. nodosus (= P. ´ schreberi Fischer [P. ´ perplexus A. Bennett]), has been described.

Perennial, rhizomatous aquatic. Leaves mostly dimorphic; submerged leaves if present, reduced to narrowly linear, opaque phyllodes, up to 2 mm broad; floating leaves leathery, long-petioled with a discoloured joint at the top of the petiole, ovate to lanceolate, 5-9 cm long, 3.2-4.7 cm broad; petiole up to 6 cm long. Stipules free, 5-9 cm long, persistent, linear-lanceolate. Spikes c. 4.5 cm long. Fruitlets obovoid, 3.5-4 mm long, 2.5-3 mm broad.

Rhizomes present. Cauline stems terete, often rust-spotted, 30--90 cm; nodal glands absent. Turions absent. Leaves both submersed and floating, ± spirally arranged. Submersed leaves sessile, rigid; stipules persistent, conspicuous, convolute, free from blade, whitish, not ligulate, 4.5--1 cm, fibrous, not shredding at tip, apex obtuse; blade light to dark green, phyllodial, not arcuate, 9--20 cm ´ 0.7--2.5 mm, base slightly tapering, without basal lobes, not clasping, margins entire, not crispate, apex not hoodlike, obtuse, lacunae absent; veins 3--5, obscure. Floating leaves: petioles lighter green immediately proximal to apex, 5.5--29 cm; blade adaxially light green, elliptic to ovate, 3.5--11 cm ´ 15--60 mm, base cordate, apex acute to rounded; veins 17--37. Inflorescences unbranched, emersed; peduncles not dimorphic, terminal, erect to ascending, cylindric, 4.5--9.5 cm; spikes not dimorphic, cylindric, 25--50 mm. Fruits sessile, green to greenish brown, obovoid, turgid, not abaxially or laterally keeled, 3.5--5 ´ 2--3 mm; beak erect to apically recurved, 0.4--0.8 mm; sides without basal tubercles; embryo with 1 full spiral. 2n = 52.

Temperate and arctic N. Hemisphere.

Distribution: Temperate and arctic regions of Europe, Asia and N. America.

Alta., B.C., Man., N.B., Nfld. and Labr. (Nfld.), N.W.T., N.S., Ont., P.E.I., Que., Sask., Yukon; Alaska, Ariz., Calif., Colo., Conn., Idaho, Ill., Ind., Iowa, Kans., Maine, Mass., Mich., Minn., Mont., Nebr., Nev., N.H., N.J., N.Mex., N.Y., N.Dak., Ohio, Oreg., Pa., R.I., S.Dak., Utah, Vt., Wash., W.Va., Wis., Wyo.; Eurasia.

3500-4400 m

Fl.Per.: August-September.

Flowering summer--fall.

Quiet or slow-flowing waters of ponds, lakes, and streams; 0--3100m.

Potamogeton natans L. Sp. PI. 126. 1753
Potamogeton natans prolixus Koch, Syn. Fl. Germ. & Helv. ed. 2. 775. 1844. Potamogeton floridanus Small, Fl. SI$. U. S. 37. 1903.
Stem simple or sparingly branched, scarcely 1 m. long ; floating leaves petioled ; blades coriaceous, revolute, lanceolate-ovate or elliptic-ovate, 4.8-10.1 cm. long, 2.4-5.6 cm. wide, obtuse and mucronate or acute at the apex, cordate or narrowly acute at the base ; petioles as long as the leaf-blades or longer ; stipules 4-7 cm. long, acute, 2-keeled, axillary and free from the petiole; submerged leaves reduced to phyllodia, terete, scarcely 1.5 mm. thick and 10-25 cm. long, deciduous; spikes 3-5 cm. long, cylindric, densely-flowered; peduncles 3-9 cm. long, as thick as the petiole ; nutlets pitted on both sides, grooved on the back ; embryo an incomplete spiral, the straight apex pointing towards the base.
Type locality : Europe.
Distribution : Nova Scotia to British Columbia, south to New Jersey, Pennsylvania, Missouri, Nebraska, and southern California; apparently in Florida (P. floridanus) ; also in Europe and Asia.

Potamogeton natans, commonly known as broad-leaved pondweed, floating pondweed, or floating-leaf pondweed, is an aquatic species in the genus Potamogeton native to quiet or slow-flowing freshwater habitats throughout the Holarctic Kingdom.