Stem: White-stemmed: whitish, zigzag branching toward the top, to 3 m long, 2-3 cm thick. Richardson's: often branched, rarely zigzagged, to 1 m long.

Flower: Small, clustered on whorls on emergent spikes. White-stemmed: in 6-12 whorls on spikes up to 5 cm long; flower stalks to 0.5 m long.
Richardson's: in 4-12 whorls on short spikes 2-4 cm long; flower stalks generally just longer than the spike, but sometimes much longer.

Fruit: Achene. White-stemmed: 4-8 mm long including stout beak, ridged on the back. Richardson's: 2.5-4 cm long, including 0.5-1 mm long beak, usually not ridged.

Root: Fibrous, from stout rhizomes. Rhizomes of white-stemmed pondweed are brown-spotted, with numerous air cavities.

Propagation: Seeds, rhizomes. White-stemmed: forms winter buds.

Importance of plant: Both provide good food and habitat for aquatic animals and waterfowl.

Distribution: Widespread in North America. 

Habitat: White-stemmed: deep, clear lakes, in up to 6 m of water. Richardson's: shallow to deep (0.5-3.5 m) water, often in alkaline lakes and marl encrusted.

May be confused with: Each other. White-stemmed pondweed has longer leaves with hooded tips and its strongly zigzag stem is also diagnostic. Other pondweeds with broad underwater leaves have floating leaves and the leaf bases of submersed leaves do not clasp the stem. Pondweeds often form hybrids, so plants with intermediate characteristics are common. 

Photographs: Closeup of Potamogeton praelongus leaves, Closeup of Potamogeton richardsonii leaves and seedheads. 

Line Drawings: None available