Flat-Stalk Pondweed

Potamogeton FriesiiThis perennial has a somewhat flattened stem over 100 cm tall. It is fairly thin, branched only a little, but it has tufts of leaves at nodes of 3-5 cm long. The sessile linear leaves are 4-5 cm long and up to 0.25 cm broad, pointed at tips, usually with 5 veins. The few-flowered inflorescence is 0.3-1 cm long. The ovoid fruits are smallish – about 0.2 cm long – and somewhat flattened and keeled. It flowers in June-August.

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