Vascular Plants of North Carolina
Account for Largeleaf Pondweed - Potamogeton amplifolius   Tuckerman
Members of Potamogeton with account distribution info or public map:
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Section 5 » Order Najadales » Family Potamogetonaceae
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AuthorTuckerman
DistributionWidely scattered in the Coastal Plain, known from 4 counties there. Also a collection in the northern mountains (Ashe County). Could potentially occur nearly statewide. Most or all members of the genus and most other aquatic species tend to be under-collected.

This is a wide-ranging Northern species, across southern Canada and the US south to NC, central AL, OK, and CA.
AbundanceRare in the Coastal Plain, and very rare in the northern mountains. Potential to occur in many other counites, but clearly it is very rare in NC overall, as the state lies at the southeastern edge of the range. This is a Significantly Rare species.
HabitatThis species is found strictly in freshwater lakes, ponds, and sluggish streams and rivers. The NCNHP's Rare Plant List (2018) says "submersed in blackwater streams", though the Ashe County site certainly is not a blackwater stream.
See also Habitat Account for General Herbaceous Ponds
PhenologyFlowers and fruits from June to September.
IdentificationThis aquatic species grows mostly submerged, though it does have some leaves that float on the surface at the top of the stem. The stem can be several feet long, mostly unbranched, with quite large alternate submerged leaves that are folded down the middle, arcing/falcate, about 4-5 inches long and half as wide, elliptical, with pointed tips and entire margins (though they can be wavy-edged). The several floating leaves are also elliptical but smaller, about 3 inches long and half as wide, quite rounded at the base, and with an obtuse tip. The leaves are strongly nerved, with the submerged ones having from 25-50 parallel nerves. The inflorescence is a densely-flowered white spike about 1.5 inches long and 2/5-inch wide, held somewhat erectly above the water surface. The quite large submerged leaves, with more than 25 nerves/veins, and arcing leaves should suffice for identification.
Taxonomic CommentsNone

Other Common Name(s)Broadleaf Pondweed, Bigleaf Pondweed
State RankS1
Global RankG5
State StatusSR-D
US Status
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