Print Report

CEGL002002 Polygonum amphibium Aquatic Vegetation

Type Concept Sentence: No Data Available

Common (Translated Scientific) Name: Water Knotweed Aquatic Vegetation

Colloquial Name: Water Knotweed Wetland

Hierarchy Level:  Association

Type Concept: This community is found primarily in the western United States and one province in Canada. It occurs over a wide elevational range from near sea level to over 2700 m. Stands are found in permanently flooded depressions, such as margins of lake shores and oxbow lakes in river floodplains. The vegetation is characterized by the dominance or codominance of Polygonum amphibium, a hydromorphically rooted emergent forb. Associates may include species of Potamogeton and other aquatic plants.

Diagnostic Characteristics: No Data Available

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: This vegetation type is only classified to the alliance level. More work is needed to describe associations. In central and western South Dakota, the species dominating this vegetation type is Polygonum amphibium var. emersum (denoted as Polygonum coccineum in South Dakota), a facultative wetland plant. It is very well adapted to fluctuating water levels and even able to climb out into the upland margins of prairie wetlands (D. Ode pers. comm.). Almost pure stands of Polygonum amphibium var. emersum can occur in areas originally dominated by a mixture of Eleocharis palustris and Polygonum amphibium var. emersum and sometimes Hordeum jubatum (D. Ode pers. comm.). This occurs with a flooding of these basins during which Eleocharis palustris becomes completely inundated, leaving the basin with significant coverage by Polygonum. With subsequent drawdown and reflooding to tolerable depths, Eleocharis can reestablish itself causing the shift back to a mixed species community (D. Ode pers. comm.).

Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: No Data Available

Floristics: This wetland vegetation type occurs in shallow water along the edges of ponds and lakes. Floating-leaved aquatic forbs cover at least 30% of the water''s surface (Kunze 1994). Polygonum amphibium often forms dense, nearly monotypic stands. Lemna minor, Potamogeton natans, Sagittaria spp., Spirodela polyrrhiza, and Wolffia spp. are occasionally present.

Dynamics:  Johnson (1939, 1941) found this community in Colorado montane lakes with significant sediment deposition, but not in lakes with rocky bottoms. Kunze (1994) suggested that this community may have occurred at higher elevations along the Columbia River Gorge, but Phalaris arundinacea, which occupies similar environments, may have displaced the Polygonum amphibium.
Environmental Description:  This wetland occurs in shallow water around the edges of ponds and lakes in western North America. Elevation varies depending on geographical location. Stands reported along the Columbia River and in the Great Plains are located just above sea level, in Montana between 640-1080 m, in northeastern Utah at 1420 m, and in Colorado from 2050-2700 m. Sites include oxbow lakes and backwater areas of the Columbia floodplains, seasonally flooded basins in the floodplains of the Green River, in glacial ponds or prairie potholes in northern Montana, in shallow lakes in the mountains of Colorado, and in flooded basins of central and western South Dakota, and possibly the Sandhills of Nebraska. Stands are located in standing water that is permanent or present at least during the growing season. The pond bottoms are composed of finer sediments, organic muck, clay, or silt.
Geographic Range: This association is found primarily in the western United States and Canada but may extend further east.

Nations: CA,US

States/Provinces:  BC, CA?, CO, ID, MT, OR, SD, UT, WA


Confidence Level: Low

Confidence Level Comments: No Data Available
Grank: G5

Greasons: No Data Available
Type Name Database Code Classification Code
Class 5 Aquatic Vegetation Class C05 5
Subclass 5.B Freshwater Aquatic Vegetation Subclass S13 5.B
Formation 5.B.2 Temperate to Polar Freshwater Aquatic Vegetation Formation F057 5.B.2
Division 5.B.2.Na North American Freshwater Aquatic Vegetation Division D049 5.B.2.Na
Macrogroup 5.B.2.Na.2 Rocky Mountain Pond-lily - Pacific Mosquito Fern - Western Waterweed Western North American Freshwater Aquatic Vegetation Macrogroup M109 5.B.2.Na.2
Group 5.B.2.Na.2.a Pond-lily species - Pondweed species - Duckweed species Freshwater Aquatic Vegetation Group G544 5.B.2.Na.2.a
Alliance A3927 Floating Pondweed - Water Knotweed Aquatic Vegetation Alliance A3927 5.B.2.Na.2.a
Association CEGL002002 Water Knotweed Aquatic Vegetation CEGL002002 5.B.2.Na.2.a
Concept Lineage: No Data Available

Predecessors: No Data Available

Obsolete Names: No Data Available

Obsolete Parents: No Data Available
Synonomy: = Persicaria amphibia Association (Cooper and Severn 1992)
= Polygonum amphibium Association (Christy 2004)
= Polygonum amphibium (McCain and Christy 2005)
= Polygonum amphibium Community (Christy 1993)
= Polygonum amphibium Community Type (Hansen et al. 1995)
= Polygonum amphibium community type (Kunze 1994) [(p.47)]
< Freshwater Aquatic Beds (Chappell et al. 1997)
< Lake Area Zone (Johnson 1936)
< Lake Area Zone (Johnson 1939)
< Lake Area Zone (Johnson 1941)
< Lake Zone (Johnson 1932b)
= Water Smartweed Semipermanently Flooded Herbaceous Vegetation (Polygonum amphibium) (Christy et al. 1998) [(p.133)]
>< Water Zone: Persicaria coccinea within Pond, sloughs and seepage areas of the Sarcobatus - Chrysothamnus Association (Ramaley 1942)
Concept Author(s): K.A. Schulz

Author of Description: K.A. Schulz and S. Menard

Acknowledgements: No Data Available

Version Date: 01-28-02
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