Michx.
Identity
Unique IDELEMENT_GLOBAL.2.138062
Element CodePMHYD0A010
Record TypeSPECIES
ClassificationSpecies
Classification StatusStandard
Name CategoryVascular Plant
IUCNLeast concern
Endemicoccurs (regularly, as a native taxon) in multiple nations
KingdomPlantae
PhylumAnthophyta
ClassMonocotyledoneae
OrderHydrocharitales
FamilyHydrocharitaceae
GenusVallisneria
Other Common NamesAmerican Eel-grass (EN) American eel-grass (EN) Tape-grass (EN) Vallisnérie d'Amérique (FR)
Concept ReferenceKartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.
Taxonomic CommentsKartesz (1994, 1999) and FNA (vol. 22, 2000) include Vallisneria neotropicalis in V. americana. Weakley (2025) accepts the two as distinct, stating "the distinctiveness of V. neotropicalis has been defended by Les et al (2008) on morphological and molecular grounds."
Conservation Status
Rank Method Rank calculation - Biotics v2
Review Date2025-08-06
Change Date1984-09-06
Edition Date2025-08-06
Edition AuthorsN. Ventrella (2025)
Threat ImpactUnknown
Range Extent>2,500,000 square km (greater than 1,000,000 square miles)
Number of Occurrences> 300
Rank ReasonsVallisneria americana is a widespread aquatic perennial forb occurring in a variety of fresh to brackish waters of North America, the West Indies, Central America, and Asia. There are over 1,300 occurrences of this species worldwide, which are threatened by development, dredging, recreation, water pollution from past mining activities, and likely other threats in some places. Little is known about trends, but with a large range extent and large number of occurrences, abundant habitat, broad habitat preferences, and no obvious intrinsic vulnerabilities, Vallisneria americana is considered secure.
Range Extent CommentsVallisneria americana occurs in North America, the West Indies, Central America, and Asia (FNA 2006). In North America, it is found from Manitoba east to Nova Scotia, Canada, and North Dakota and Maine south to Florida, Texas, and Arizona in the United States and south to Mexico (FNA 2006, Weakley and the Southeastern Flora Team 2025). It also occurs from British Columbia, Canada, and Washington south to Nevada in the United States (FNA 2006), though it may be introduced to some of these regions (Kartesz 1996). Range extent was estimated to be over 12 million square kilometers using herbarium specimens, photo-based observations, and NatureServe Network occurrence data collected between 1994 and 2025 (GBIF 2025, iNaturalist 2025, NatureServe 2025, RARECAT 2025, SEINet 2025).
Occurrences CommentsBy applying a 1 km separation distance to herbarium specimens, photo-based observations, and NatureServe Network occurrence data documented between 1994 and 2025, it is estimated that there are more than 1,300 occurrences rangewide (GBIF 2025, iNaturalist 2025, NatureServe 2025, RARECAT 2025, SEINet 2025).
Threat Impact CommentsThreats to this species are not well documented but include development, dredging, recreation, water pollution from past mining activities, and likely other threats in some places (NatureServe 2025). There is insufficient data, including anecdotal accounts, to understand the scope and severity of threats for this taxon.