| Author | L. | |
| Distribution | Known from a single collection in 1934, from Lake Louise in Buncombe County. As the website editors are aware that the next nearest record is from northeastern WV, this may well be from an introduction. Disturbed habitats by Lake Louise have supported many of non-native or questionably native species. Weakley (2018) only shows it as Historical in NC and does not suggest that it might be of uncertain occurrence in the state.
This is a widespread but Northern species, ranging from Canada south only to DE, WV (one county), IL, and CA. There are no records known for VA, KY, or TN.
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| Abundance | Long historical, if not extirpated. The NCNHP in late 2022 moved the State Rank from SH to SU (Undetermined) and placed the species on the Watch List (W4), of uncertain provenance in the state. As mentioned in Distribution, the website editors believe the species might not have been native to NC, though Weakley (2018) does not mention this. As a result, the specimen from Buncombe County has been re-assigned by the editors to Provenance Uncertain rather than Natural, on the range map below. | |
| Habitat | The NC record was from a reservoir. Over its range, it occurs in still waters of lakes, ponds, and slow-moving rivers. |
| Phenology | Flowers and fruits from June to September. | |
| Identification | More than essentially any other pondweed in the East, this species has highly different submerged and emergent/floating leaves. The floating leaves are like many others, being elliptical and medium-sized, but the submerged leaves are highly filiform, about 6-8 inches long and needle-like. The spikes are rather large and about 1.5 inches long and cylindrical in shape, conspicuous above the water surface. You will need to pull this plant out of the water to see the highly fibrous submerged leaves, as the floating leaves are not distinctive from some other species. | |
| Taxonomic Comments | None
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| Other Common Name(s) | Floating-leaf Pondweed, Broadleaf Pondweed | |
| State Rank | SU [SH] | |
| Global Rank | G5 | |
| State Status | W4 | |
| US Status | | |
| USACE-agcp | OBL link |
| USACE-emp | OBL link |
