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Sparganium fluctuans

(Morong) B.L. Robins.

Floating Bur-reed

G5Secure Found in 2 roadless areas NatureServe Explorer →
G5SecureGlobal Rank
Least concernIUCN
UnknownThreat Impact
Identity
Unique IDELEMENT_GLOBAL.2.128119
Element CodePMSPA01060
Record TypeSPECIES
ClassificationSpecies
Classification StatusStandard
Name CategoryVascular Plant
IUCNLeast concern
Endemicoccurs (regularly, as a native taxon) in multiple nations
KingdomPlantae
PhylumAnthophyta
ClassMonocotyledoneae
OrderTyphales
FamilyTyphaceae
GenusSparganium
Other Common Names
floating bur-reed (EN) Rubanier flottant (FR)
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 Date2025-01-10
Change Date1984-09-06
Edition Date2025-01-10
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 Reasons
Sparganium fluctuans is an aquatic perennial monocot occurring in streams, lakes, ponds, rivers, and marshes of North America from Washington, Idaho, and British Columbia east to Newfoundland and Pennsylvania in the United States and Canada. There are just over 300 estimated occurrences rangewide, which are potentially threatened by development, water diversion, alteration of hydrology, erosion, pollution, recreational activities, invasive species, drought, and other threats in some places. Little is known about threats and trends, but with a large range extent, high number of occurrences, abundant habitat, broad habitat preferences, and no obvious intrinsic vulnerabilities, Sparganium fluctuans is considered secure.
Range Extent Comments
Sparganium fluctuans occurs in northern North America from Washington, Idaho, and British Columbia east to Newfoundland and Pennsylvania in the United States and Canada (Kartesz 1996, FNA 2000, Weakley and the Southeastern Flora Team 2024). 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, 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 just over 300 occurrences rangewide (GBIF 2025, iNaturalist 2025, NatureServe 2025, SEINet 2025).
Threat Impact Comments
Although threats are not widely documented, Sparganium fluctuans is likely threatened by development, water diversion, alteration of hydrology, erosion, pollution, recreational activities, invasive species, drought, and other threats in some places, though there is insufficient data, including anecdotal accounts, to understand the scope and severity of threats for this species.
Ecology & Habitat

Habitat

Sparganium fluctuans occurs in a variety of freshwater environments, including streams, lakes, ponds, rivers, and marshes, at elevations up to 1,173 meters (Les 2020). While this species typically occurs in water depths ranging from 0.5 to 2 meters, it can survive temporarily when stranded on mud during low water periods. Sparganium fluctuans can grow in various substrate types such as clay, gravel, sand, and muck, and it prefers quiet, cold waters that are either acidic or slightly alkaline (pH 4.9–8.5). These waters tend to be oligotrophic, with low alkalinity, chloride, magnesium, and sulfate levels.

Reproduction

Flowering and fruiting occurs from July to September (Les 2020).
Palustrine Habitats
HERBACEOUS WETLANDFORESTED WETLANDRiparian
Other Nations (2)
United StatesN4
ProvinceRankNative
ConnecticutS1Yes
PennsylvaniaS4Yes
WashingtonS1Yes
VermontS3Yes
MaineSNRYes
MinnesotaSNRYes
MichiganSNRYes
MassachusettsS2Yes
New YorkS4Yes
New HampshireSNRYes
WisconsinSNRYes
IdahoSNRYes
CanadaN5
ProvinceRankNative
Prince Edward IslandS2Yes
LabradorS2Yes
New BrunswickS4Yes
OntarioS5Yes
SaskatchewanS4Yes
British ColumbiaS4Yes
Island of NewfoundlandS2Yes
Nova ScotiaS4Yes
QuebecS4Yes
ManitobaS1Yes
AlbertaS1Yes
Threat Assessments
ThreatScopeSeverityTiming
Unknown/undetermined———

—

Plant Characteristics
DurationPERENNIAL
Economic Value (Genus)No
Roadless Areas (2)
Minnesota (2)
AreaForestAcres
Hegman LakesSuperior National Forest675
Kawishiwi Lake To SawbillSuperior National Forest15,305
References (4)
  1. Flora of North America Editorial Committee (FNA). 2000. Flora of North America north of Mexico. Vol. 22. Magnoliophyta: Alismatidae, Arecidae, Commelinidae (in part), and Zingiberidae. Oxford Univ. Press, New York. xxiii + 352 pp.
  2. 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.
  3. Kartesz, J.T. 1996. Species distribution data at state and province level for vascular plant taxa of the United States, Canada, and Greenland (accepted records), from unpublished data files at the North Carolina Botanical Garden, December, 1996. Original distribution data was for Districts of Franklin and Keewatin; subnational element tracking records using this reference should be reviewed for whether the element occurs in the Northwest Territories in addition to Nunavut (i.e., some reports for Franklin might be for the NWT rather than Nunavut).
  4. Les, D. 2020. Aquatic Monocotyledons of North America: Ecology, Life History, and Systematics. CRC Press, Boca Raton, FL. 568 pp.