Fern.
Conservation Status
Rank Method Rank calculation - Biotics v2
Review Date2024-02-06
Change Date2023-12-12
Edition Date2024-02-14
Edition AuthorsHarmon, P.J.; K. Maybury (1996); rev. S. Neid (1997), rev. C. Nordman (2012), rev. Soteropoulos (2023), rev. SE Ranking Workshop (2024)
Threat ImpactHigh - medium
Range Extent20,000-200,000 square km (about 8000-80,000 square miles)
Number of Occurrences6 - 80
Rank ReasonsPotamogeton tennesseensis is a perennial aquatic herb endemic to shallow waters in streams, ponds, and rivers in the Appalachian Mountains and Interior Low Plateau in the southeastern United States. Across its moderate range including Kentucky, Ohio, Pennsylvania, Tennessee, Virginia, and West Virginia, only 49 occurrences have been documented in the last thirty years, and only ten occurrences have excellent or good viability. Several occurrences have been lost from dams, surface mining, bridge projects, and habitat conversion. It is threatened by alteration of stream flow and water quality, and it needs watershed protections to prevent runoff. Monitoring of populations should be conducted to improve our understanding of reproduction, plant abundance, threats, and trends, as well as continuing conservation measures to protect the species.
Range Extent CommentsPotamogeton tennesseensis occurs in the Appalachian Mountains and Interior Low Plateau in the southeastern United States where it has been documented in Kentucky (Laurel, McCreary, and Whitley Counties), Ohio (Adams, Jackson, Pike, Scioto, and Vinton Counties), Pennsylvania (Allegheny, Beaver, Bedford, Fayette, Fulton), Tennessee (Blount, Cumberland, Fentress, Monroe, Morgan, Polk, and Scott Counties), Virginia (Augusta, Bath, Bland, and Giles Counties), and West Virginia (Braxton, Grant, Greenbrier, Harrison, Monongalia, Nicholas, Ohio, Pocahontas, Preston, Raleigh, Tucker, Upshur, and Webster Counties). It is confined mostly to the Cumberland Plateau (Weakley, pers. comm., 2024). It is suspected to be in Maryland (FNA 2000).
Occurrences CommentsBy applying a 1 km separation distance to herbarium specimen data, photo-based observation data, and NatureServe Network occurrence data documented between the years of 1993 and 2023, it is estimated that there are 49 occurrences rangewide, excluding two occurrences that were failed to find (GBIF 2023, iNaturalist 2023, NatureServe 2023, SEINet 2023). Extant occurrences by state include three in Kentucky, eighteen in Ohio, six in Pennsylvania, twelve in Tenneessee, one in Virginia, and nine in West Virginia. Both Kentucky and Virginia have searched for historic records and found many extirpated, and each state has only documented one new occurrence each in the past ten years (Littlefield and Townsend, pers. comm., 2024).
Threat Impact CommentsPotamogeton tennesseensis is threatened by habitat loss and degradation, especially from alterations to stream flow and water quality. Several occurrences have been lost from impacts such as dams, surface mining in creeks, bridge replacement projects, and ditching, draining, and filling to convert to agriculture. Its aquatic habitat is highly threatened by agricultural or silvicultural run-off leading to siltation (turbidity) and other pollutants, such as herbicide or nutrient loading from cattle, which have also been observed trampling plants in creeks. Alterations to flow, including dams and water diversions, beaver dams, droughts, and extreme weather events that move boulders or remove soil from riverscour, also degrade habitat. Some historic sites at the confluence of larger and smaller riverine systems in Tennessee likely washed out due to extreme storm events (Crabtree, pers. comm., 2024), and increased strength of storms might be a future threat. Stream impacts from mining, oil and gas activities may threaten certain populations. Recreational activities such as fishing and swimming may have low impacts, though fording creeks with vehicles could be determinantal. Invasive species, especially Hydrilla verticillata and also including Potamogeton crispus, Phalaris arundinacea, Elaeagnus, and Rosa multiflora, may be impacting some populations. It is somewhat threatened by land-use conversion and habitat fragmentation (Southern Appalachian Species Viability Project 2002).