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Potamogeton obtusifolius

Mert. & Koch

Bluntleaf Pondweed

G5Secure Found in 1 roadless area NatureServe Explorer →
G5SecureGlobal Rank
Least concernIUCN
UnknownThreat Impact
Identity
Unique IDELEMENT_GLOBAL.2.132578
Element CodePMPOT030R0
Record TypeSPECIES
ClassificationSpecies
Classification StatusStandard
Name CategoryVascular Plant
IUCNLeast concern
Endemicoccurs (regularly, as a native taxon) in multiple nations
KingdomPlantae
PhylumAnthophyta
ClassMonocotyledoneae
OrderNajadales
FamilyPotamogetonaceae
GenusPotamogeton
Other Common Names
bluntleaf pondweed (EN) Blunt-leaved Pondweed (EN) Potamot à feuilles obtuses (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 Date2024-09-30
Change Date1984-06-25
Edition Date2024-09-30
Edition AuthorsN. Ventrella (2024)
Threat ImpactUnknown
Range Extent>2,500,000 square km (greater than 1,000,000 square miles)
Number of Occurrences> 300
Rank Reasons
Potamogeton obtusifolius is a perennial or annual aquatic forb occurring in slow-moving, alkaline waters of bogs, rivers, lakes, ponds, springs, streams of North America; from Alaska and the Northwest Territories south through Washington and Wyoming, east to New Jersey, and north to Newfoundland and Labrador. It also occurs in Eurasia. There are over 3,000 occurrences of this taxon, which are threatened by recreational activities (uprooted by boats), invasive species, alteration of hydrology, aquatic herbicides, eutrophication, and likely other threats in some places. Little is known about threats or trends, but with a large range extent, high number of occurrences, abundant habitat, broad habitat preferences, and no obvious intrinsic vulnerabilities, Potamogeton obtusifolius is considered secure.
Range Extent Comments
Potamogeton obtusifolius is a circumboreal species, occurring in North America and Eurasia (FNA 2000). In North America, it occurs from Alaska and the Northwest Territories south through Washington and Wyoming, east to New Jersey, and north to Newfoundland and Labrador. Range extent was estimated to be over 47 million square kilometers using herbarium specimens, photo-based observations, and NatureServe Network occurrence data collected between 1993 and 2024 (GBIF 2024, iNaturalist 2024, NatureServe 2024, SEINet 2024).
Occurrences Comments
By applying a 1 km separation distance to herbarium specimens, photo-based observations, and NatureServe Network occurrence data documented between 1993 and 2024, it is estimated that there are over 3,000 occurrences rangewide (GBIF 2024, iNaturalist 2024, NatureServe 2024, SEINet 2024).
Threat Impact Comments
Although threats are not widely documented, Potamogeton obtusifolius is threatened by recreational activities (uprooted by boats), invasive species, alteration of hydrology, aquatic herbicides, eutrophication, and likely other threats in some places, though there is insufficient data, including anecdotal accounts, to understand scope and severity of threats for this species (NatureServe 2024).
Ecology & Habitat

Description

Blunt-leaved Pondweed is an aquatic, rhizomatous perennial with slender, submergent, or floating stems that are up to 100 cm long. The leaves are linear, 3-10 cm long, and 2-4 mm wide, each with a small round gland on either side at the base. There is a white-membranous leaf stipule that surrounds the stem above the point where the leaf diverges. Herbage is glabrous. The minute flowers are borne on long-stalked, narrow, interrupted spikes in the axils of the upper leaves. The flowers consist only of the stamens and an ovary; there are no petals or sepals. The achene is oval in outline, 3-4 mm long, and compressed with a keel on the outer edge.

Diagnostic Characteristics

The narrow-leaved pondweeds are a very difficult group to distinguish; a technical key must be employed.

Habitat

Potamogeton obtusifolius occurs in "bays, bogs, brooks, lakes (brownwater), pits (clay, gravel), ponds (beaver, glacial, ice, log, roadside), pools, potholes, rivers (backwaters, slow-moving), sloughs (backwater), springs, and streams (boggy, shallow, sluggish)" (Les 2020). This species occurs in both cold, oligotrophic (nutrient-poor) and warmer, eutrophic (nutrient-rich) environments, tolerating low salinity and varying water conditions. Potamogeton obtusifolius is generally found in shallow, still to slow-moving waters of moderate alkalinity with fairly high levels of dissolved nutrients and organic matter.

Reproduction

This species produces a high amount of seed, which are dispersed by water or transported by birds and fish (Les 2020).
Palustrine Habitats
FORESTED WETLANDBog/fen
Other Nations (2)
United StatesN5
ProvinceRankNative
New YorkS4Yes
MassachusettsS1Yes
WisconsinSNRYes
KansasSNRYes
VermontS3Yes
WashingtonS2Yes
WyomingS1Yes
New HampshireSHYes
New JerseyS1Yes
Rhode IslandSNRYes
IdahoSNRYes
MinnesotaSNRYes
MaineSNRYes
PennsylvaniaS1Yes
MontanaS3Yes
MarylandSNRYes
NebraskaSNRYes
ConnecticutSNRYes
MichiganSNRYes
AlaskaS3Yes
CanadaN5
ProvinceRankNative
LabradorS1Yes
ManitobaS2Yes
SaskatchewanS3Yes
QuebecS4Yes
Northwest TerritoriesS3Yes
Yukon TerritoryS2Yes
Prince Edward IslandS3Yes
Island of NewfoundlandS1Yes
British ColumbiaS4Yes
AlbertaS3Yes
OntarioS4Yes
Nova ScotiaS4Yes
New BrunswickS4Yes
NunavutSHYes
Threat Assessments
ThreatScopeSeverityTiming
6 - Human intrusions & disturbanceUnknownUnknownUnknown
6.1 - Recreational activitiesUnknownUnknownUnknown
7 - Natural system modificationsUnknownUnknownUnknown
7.2 - Dams & water management/useUnknownUnknownUnknown
8 - Invasive & other problematic species, genes & diseasesUnknownUnknownUnknown
8.1 - Invasive non-native/alien species/diseasesUnknownUnknownUnknown
8.1.1 - Unspecified speciesUnknownUnknownUnknown
9 - PollutionUnknownUnknownUnknown
9.3 - Agricultural & forestry effluentsUnknownUnknownUnknown
9.3.1 - Nutrient loadsUnknownUnknownUnknown
9.3.3 - Herbicides and pesticidesUnknownUnknownUnknown

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Plant Characteristics
DurationANNUAL, PERENNIAL
Economic Value (Genus)No
Roadless Areas (1)
Montana (1)
AreaForestAcres
Bear - Marshall - Scapegoat - SwanLolo National Forest118,485
References (12)
  1. Aulio, K. and M. Salin. 1982. Enrichment of copper, zinc, manganese, and iron in five species of pondweeds (POTAMOGETON spp.). Bull. Environm. Contam. Toxicol. 29:320-325.
  2. Danell, K. 1977. Short-term plant successions following the colonization of a northern Swedish lake by the muskrat, ONDATRA ZIBETHICA. Journal of Applied Ecology 14:933-947.
  3. 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.
  4. Global Biodiversity Information Facility (GBIF). 2024. Global Biodiversity Information Facility (GBIF) data portal. Online. Available: https://www.gbif.org/ (accessed 2024).
  5. iNaturalist. 2024. Online. Available: https://www.inaturalist.org (accessed 2024).
  6. 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.
  7. Les, D. 2020. Aquatic Monocotyledons of North America: Ecology, Life History, and Systematics. CRC Press, Boca Raton, FL. 568 pp.
  8. NatureServe. 2024. NatureServe Network Biodiversity Location Data. NatureServe, Arlington, Virginia.
  9. Pip, E. 1987. The ecology of POTAMOGETON species in central North America. Hydrobiologia 153:203-216.
  10. Southwest Environmental Information Network (SEINet). 2024. Collections Databases. Online. Available: https://swbiodiversity.org/seinet/collections/index.php (accessed 2024).
  11. Toivonen, H. and C. Nybom. 1989. Aquatic vegetation and its recent succession in the waterfowl wetland Koijarvi, S. Finland. Ann. Bot. Fennici 26:1-14.
  12. Toivonen, H. and S. Back. 1989. Changes in aquatic vegetation of a small eutrophicated and lowered lake (southern Finland). Ann. Bot. Fennici 26:27-38.