Vascular Plants of North Carolina
Account for Small Pondweed - Potamogeton pusillus    L.
Members of Potamogeton with account distribution info or public map:
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Section 5 » Order Najadales » Family Potamogetonaceae
AuthorL.
DistributionNearly statewide, but primarily in the eastern half of the state. Nearly throughout the Coastal Plain, scattered in the Piedmont, but only a few mountain records (in the southern counties).

This is a very widespread species, ranging from Canada south to southern FL and TX. Note that the BONAP map is incorrect for this species.
AbundanceFairly common to common along and near the coast, but only uncommon to infrequent farther inland in the Coastal Plain and eastern half of the Piedmont. Very rare to rare in the western Piedmont and mountains.
HabitatThis is a species of many types of still waters -- pools, ponds, lakes, and slow-moving streams. It can occur in brackish to oligohaline waters.
See also Habitat Account for General Herbaceous Ponds
PhenologyFlowers and fruits from May to September.
IdentificationThis species and P. berchtoldii are very similar and can be difficult to separate. Both have submerged leaves only (thus no floating leaves), and these are both alternate and opposite, linear, only about 1.5 inches long but barely 1/20-inch wide. The stem is quite branched in the upper portions. The leaves have only a single strong nerve, with single indistinct nerves on each side. There are stipules at the leaf bases, about 2/5-inch long, but they quickly fall off. However, at the base of each leaf is (usually) a nodal gland, which is lacking in the quite similar P. foliosus; you will need a hand lens to see this character. There are numerous spikes (to about 2/5-inch long) from upper leaf axils; in this species the spike is interrupted, whereas in P. berchtoldii the inflorescence is continuous. P. foliosus has a short, conical spike barely 1/5-inch long. See Weakley (2018) for additional character differences.
Taxonomic CommentsMost references have long recognized P. pusillus, but oddly RAB (1968) did not, and had the entity subsumed within P. berchtoldii.

Other Common Name(s)Slender Pondweed, Lesser Pondweed, Least Pondweed
State RankS4
Global RankG5
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