As the frequent Potamogeton perfoliatus also the rare Potamogeton praelongus has only subaequeous leaves, but no swimming leaves. At both species only the flowers are protruding outside the water. Potamogeton praelongus grows in 1,5 to 4 meter deep water. The long and rarely branched stems have a whitish color, and the onset of the leaves is stem-clasping. Sometimes teared stems are washed up to the lakeshore, as shown here.