Potamogeton lucens, L.

5. P. lucens L. View in CoL , Sp. Pl. 126 (1753) View Cited Treatment .

Leaves all submerged, up to 20 x 6 cm, short- or long-petiolate, elliptical or obovateelliptical to narrowly elliptic-oblong, cuneate at the base, acute or acuminate or cuspidate, more or less distinctly serrulate, with regularly ascending secondary veins (occasional leaves reduced to phyllodes). Stipules large and conspicuous, herbaceous. Peduncles thickened upwards. Fruitlets 3 -5-4 mm. 2/i = 52. Base-rich water. Most of Europe. All except Co Fa Is Sb Tu.

P. x zizii Koch ex Roth , Enum. 531 (1827) (5 x 6) andP. x salicifolius Wolfg. in Schultes & Schultes fit, Mantissa 3: 355 (1827) ( P. decipiens Nolte ex Koch ) (5 x 9) are two of the most frequent Potamogeton hybrids and P. x zizii is the only one known to produce well-formed fruits. Both these hybrids in some of their forms can be confused with 5.