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Glyceria laxa

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Limp Mannagrass

G4Apparently Secure Found in 2 roadless areas NatureServe Explorer →
G4Apparently SecureGlobal Rank
UnknownThreat Impact
Identity
Unique IDELEMENT_GLOBAL.2.144205
Element CodePMPOA2Y0M0
Record TypeSPECIES
ClassificationSpecies
Classification StatusStandard
Name CategoryVascular Plant
Endemicoccurs (regularly, as a native taxon) in multiple nations
KingdomPlantae
PhylumAnthophyta
ClassMonocotyledoneae
OrderCyperales
FamilyPoaceae
GenusGlyceria
Synonyms
Glyceria x laxa
Other Common Names
limp mannagrass (EN) Northern Mannagrass (EN)
Concept Reference
Kartesz, 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.
Conservation Status
Rank Method Rank calculation - Biotics v2
Review Date2025-05-08
Change Date2025-05-08
Edition Date2025-05-08
Edition AuthorsN. Ventrella (2025)
Threat ImpactUnknown
Range Extent200,000-2,500,000 square km (about 80,000-1,000,000 square miles)
Number of Occurrences81 - 300
Rank Reasons
Glyceria laxa is a perennial grass occurring in swamps, bogs, seeps, wet meadows, and wet woods of eastern North America; from Prince Edward Island south (primarily) along the eastern seaboard to Tennessee and in the Appalachian region in the United States and Canada. There are 92 estimated occurrences of this taxon rangewide, which are threatened by land-use conversion, habitat fragmentation, forest management practices, invasive plants, rights-of-way maintenance activities, and succession. Little is known about rangewide threats and trends, and monitoring populations is important to improving our understanding of the status of Glyceria laxa.
Range Extent Comments
Glyceria laxa occurs in eastern North America, in Canada and the United States from Prince Edward Island south (primarily) along the eastern seaboard and in the Appalachian region to Tennessee (FNA 2007, Weakley and the Southeastern Flora Team 2025). There are also historical records of this species from Minnesota, Wisconsin, and Ontario (SEINet 2025). Range extent was estimated 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 Comments
By 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 92 occurrences rangewide (GBIF 2025, iNaturalist 2025, NatureServe 2025, RARECAT 2025, SEINet 2025).
Threat Impact Comments
Glyceria laxa is somewhat threatened by land-use conversion, habitat fragmentation, and forest management practices (Southern Appalachian Species Viability Project 2002). Additional threats include invasive plants, rights-of-way maintenance activities, and succession (NatureServe 2025).
Ecology & Habitat

Habitat

Glyceria laxa occurs in "swamps, bogs, and wet woods, primarily along the eastern seaboard of North America" (FNA 2007). It also occurs in seeps and wet meadows (Weakley and the Southeastern Flora Team 2025).
Terrestrial Habitats
Forest/WoodlandGrassland/herbaceous
Palustrine Habitats
FORESTED WETLANDBog/fen
Other Nations (2)
United StatesN4
ProvinceRankNative
DelawareSHYes
District of ColumbiaSXYes
VirginiaS1Yes
VermontSNRYes
WisconsinSNRYes
ConnecticutSNRYes
MaineSNRYes
New JerseyS1Yes
North CarolinaS2Yes
West VirginiaS3Yes
New HampshireSNRYes
TennesseeSNRYes
MassachusettsSNRYes
PennsylvaniaSNRYes
MarylandSNRYes
New YorkS1Yes
CanadaNNR
ProvinceRankNative
OntarioSNRYes
Prince Edward IslandSNRYes
Nova ScotiaSNRYes
New BrunswickSNRYes
Threat Assessments
ThreatScopeSeverityTiming
4 - Transportation & service corridorsUnknownUnknownUnknown
5 - Biological resource useUnknownUnknownUnknown
5.3 - Logging & wood harvestingUnknownUnknownUnknown
7 - Natural system modificationsUnknownUnknownUnknown
7.1 - Fire & fire suppressionUnknownUnknownUnknown
7.1.2 - Suppression in fire frequency/intensityUnknownUnknownUnknown
8 - Invasive & other problematic species, genes & diseasesUnknownUnknownUnknown
8.1 - Invasive non-native/alien species/diseasesUnknownUnknownUnknown
8.1.1 - Unspecified speciesUnknownUnknownUnknown

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Plant Characteristics
DurationPERENNIAL
Economic Value (Genus)No
Roadless Areas (2)
North Carolina (1)
AreaForestAcres
Lost CovePisgah National Forest5,944
Virginia (1)
AreaForestAcres
Peters Mountain Addition BJefferson National Forest2,909
References (10)
  1. Dodds, J.S. 2025. <i>Glyceria laxa</i> Rare Plant Profile. New Jersey Department of Environmental Protection, State Parks, Forests & Historic Sites, Forests & Natural Lands, Office of Natural Lands Management, New Jersey Natural Heritage Program, Trenton, NJ. 17 pp. [https://dep.nj.gov/wp-content/uploads/nlm/glyceria-laxa-northern-manna-grass.pdf]
  2. Flora of North America Editorial Committee (FNA). 2007a. Flora of North America north of Mexico. Vol. 24. Magnoliophyta: Commelinidae (in part): Poaceae, part 1. Oxford Univ. Press, New York. xxviii + 911 pp.
  3. Global Biodiversity Information Facility (GBIF). 2025. Global Biodiversity Information Facility (GBIF) data portal. Online. Available: https://www.gbif.org/ (accessed 2025).
  4. iNaturalist. 2025. Online. Available: https://www.inaturalist.org (accessed 2025).
  5. Kartesz, 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.
  6. NatureServe. 2025. NatureServe Network Biodiversity Location Data. NatureServe, Arlington, Virginia.
  7. <p>NatureServe's Rapid Analysis of Rarity and Endangerment Conservation Assessment Tool (RARECAT). 2025. Version: 2.1.1 (released April 04, 2025).</p>
  8. Southern Appalachian Species Viability Project. 2002. A partnership between the U.S. Forest Service-Region 8, Natural Heritage Programs in the Southeast, NatureServe, and independent scientists to develop and review data on 1300+ regionally and locally rare species in the Southern Appalachian and Alabama region. Database (Access 97) provided to the U.S. Forest Service by NatureServe, Durham, North Carolina.
  9. Southwest Environmental Information Network (SEINet). 2025. Collections Databases. Online. Available: https://swbiodiversity.org/seinet/collections/index.php (accessed 2025).
  10. Weakley, A.S., and Southeastern Flora Team. 2025. Flora of the southeastern United States Web App. Edition of February 18, 2025. University of North Carolina Herbarium (NCU), North Carolina Botanical Garden, University of North Carolina, Chapel Hill. Online. Available: https://fsus.ncbg.unc.edu (accessed 2025).