Print Report

A1747 Lemna minor - Wolffia borealis - Wolffia columbiana Aquatic Vegetation Alliance

Type Concept Sentence: This alliance of aquatic floating vegetation is dominated by Lemna minor or other Lemna species, Wolffia borealis, and/or Wolffia columbiana, often mixed with other Lemnaceae or other aquatic plants found at low elevations (below 200 m [650 feet]) floating at the surface of quiet streams and ponds in the western U.S. and Canada.

Common (Translated Scientific) Name: Common Duckweed - Northern Watermeal - Columbian Watermeal Aquatic Vegetation Alliance

Colloquial Name: Western Duckweed - Watermeal Aquatic Vegetation

Hierarchy Level:  Alliance

Type Concept: This alliance of floating vegetation is dominated by Lemna minor or other Lemna species, Wolffia borealis, and/or Wolffia columbiana. Associated species include Azolla spp., Riccia fluitans, Ricciocarpos natans, and Spirodela polyrrhiza. Biomass can be abundant under eutrophic conditions. Total cover may be continuous, intermittent or open. These small floating plants may float on the water''s surface or become stranded and possibly rooted during drawdown periods. Ponds are found at low elevations (below 200 m [650 feet]), and stands are floating on the water surface of quiet streams and ponds.

Diagnostic Characteristics: Floating waterbeds of Lemna minor or other Lemna species, Wolffia borealis, and/or Wolffia columbiana.

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: Very little information has been collected on the community ecology and distribution of this alliance. More field-based studies are needed. Wolffia columbiana is considered a rare plant in Washington.

Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: This alliance is of aquatic floating herbaceous plants that form a very low (less than 5 cm) canopy on the water surface that may be continuous or open. Emergent plants may be present.

Floristics: Examples of this alliance are dominated by any one or several species of the genus Lemna floating on the water''s surface. The composition of examples varies across the wide range of this alliance. Other species present may include Azolla caroliniana, Azolla filiculoides, Azolla microphylla (= Azolla mexicana), Spirodela spp., Wolffia borealis, and other Wolffia spp., as well as Riccia spp. (an aquatic liverwort). Total cover may be continuous, intermittent or open. Other species present may include several species of Potamogeton, Sagittaria, or Polygonum. While these latter species are rooted submerged species, and technically not part of the strictly floating community, they do intermingle.

Dynamics:  All of the dominant species can survive stranding on mud but cannot survive complete desiccation. Lemna spp. can reproduce asexually by budding from a pouch at the plant''s base. These plants may also overwinter as dense, rootless, starch-filled daughter plants. If the water persists long enough, sexual reproduction produces seeds which can survive drawdown and drying of the substrate.
Environmental Description:  Stands occur in seasonal and perennial freshwater habitats with still water and saturated soils. Stands occur in ditches, rivers, streams, channels, and ponds from sea level to 2300 m elevation. The standing water habitat is relatively shallow, generally less than 2-4 m (6.6-13.1 feet) and occurs as ponds, lakes, ditches, stock ponds, and backwater sloughs of river and stream channels. Standing water for much or most of the growing season is characteristic. Depth of the water is of no consequence to floating plants; they occur where the wind pushes them.
Geographic Range: This alliance occurs widely throughout the western U.S. (west of the 100th meridian) and southwestern Canada. It was possibly introduced by migratory waterfowl into southern California.

Nations: CA,US

States/Provinces:  AZ, BC, CA, CO, ID, MT, ND, NE, NM, NV, OK, OR, SD, TX, UT, WA, WY


Confidence Level: Low

Confidence Level Comments: No Data Available
Grank: GNR

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 A1747 Common Duckweed - Northern Watermeal - Columbian Watermeal Aquatic Vegetation Alliance A1747 5.B.2.Na.2.a
Association CEGL003305 Common Duckweed Aquatic Vegetation CEGL003305 5.B.2.Na.2.a
Association CEGL003311 (Northern Watermeal, Columbian Watermeal) Aquatic Vegetation CEGL003311 5.B.2.Na.2.a
Association CEGL005450 Duckweed species Western North America Aquatic Vegetation CEGL005450 5.B.2.Na.2.a
Concept Lineage: equivalent to A.1747

Predecessors: No Data Available

Obsolete Names: No Data Available

Obsolete Parents: No Data Available
Synonomy: = Lemna (minor) and Relatives (Duckweed blooms) Provisional Alliance (Sawyer et al. 2009) [52.105.00]
= Lemna (minor) and Relatives Provisional Alliance (Duckweed blooms) (Buck-Diaz et al. 2012)
= Lemna (minor) and Relatives Provisional Herbaceous Alliance (CNPS 2017) [52.105.00]
>< Coastal and Valley Freshwater Marsh (#52410) (Holland 1986b)
= Duckweed series (Sawyer and Keeler-Wolf 1995)
>< Montane Freshwater Marsh (#52430) (Holland 1986b)
>< Transmontane Freshwater Marsh (#52420) (Holland 1986b)
Concept Author(s): M. Schindel and M. Pyne, in Faber-Langendoen et al. (2013)

Author of Description: G. Kittel

Acknowledgements: No Data Available

Version Date: 03-14-14
  • Armstrong, W. P. 1982. Duckweeds, California''s smallest wildflowers. Fremontia 10:16-22.
  • Armstrong, W. P., and R. F. Thorne. 1984. The genus Wolffia (Lemnaceae) in California. Madroño 31:171-179.
  • Buck-Diaz, J., S. Batiuk, and J. M. Evens. 2012. Vegetation alliances and associations of the Great Valley ecoregion, California. California Native Society, Sacramento, CA. [http://cnps.org/cnps/vegetation/pdf/great_valley_eco-vegclass2012.pdf]
  • CNPS [California Native Plant Society]. 2015-2017. A manual of California vegetation [online]. California Native Plant Society, Sacramento, CA. [http://vegetation.cnps.org/].
  • DiTomaso, J. M., and E. A. Healy. 2007. Weeds of California and other western States. Two volumes. Publication 3488. University of California, Agriculture and Natural Resources, Oakland, CA. 1808 pp.
  • Faber-Langendoen, D., J. Drake, M. Hall, G. Kittel, S. Menard, C. Nordman, M. Pyne, M. Reid, M. Russo, K. Schulz, L. Sneddon, K. Snow, and J. Teague. 2013-2019b. Screening alliances for induction into the U.S. National Vegetation Classification: Part 1 - Alliance concept review. NatureServe, Arlington, VA.
  • Hickman, J. C. 1993. The Jepson manual: Higher plants of California. University of California Press, Ltd., Berkeley, CA. 1400 pp.
  • Holland, R. F. 1986b. Preliminary descriptions of the terrestrial natural communities of California. Unpublished report prepared for the California Department of Fish and Game, Nongame-Heritage Program and Natural Diversity Database, Sacramento. 156 pp.
  • Mason, H. L. 1957. A flora of the marshes of California. University of California Press, Berkeley, CA.
  • Sawyer, J. O., T. Keeler-Wolf, and J. Evens. 2009. A manual of California vegetation. Second edition. California Native Plant Society, Sacramento CA. 1300 pp.
  • Sawyer, J. O., and T. Keeler-Wolf. 1995. A manual of California vegetation. California Native Plant Society, Sacramento. 471 pp.