Common (Translated Scientific) Name: Duckweed species Eastern North American Aquatic Vegetation

Colloquial Name: Eastern North America Duckweed Pond

Hierarchy Level:  Association

Type Concept: This aquatic association of floating vegetation is known to occur throughout temperate eastern North America. Lemna spp. typically dominate but may be mixed with other plant taxa floating on the water surface. Lemna-dominated aquatic vegetation occupies wetlands that are permanently, semipermanently or seasonally flooded. These small plants may float on the water''s surface or become stranded and possibly rooted during drawdown periods. Water chemistry is fresh. 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. The composition of examples varies across this wide distributional range. Lemna taxa that may be present in eastern North America include Lemna aequinoctialis (southwest U.S. as well as southeast U.S.), Lemna minor (widespread across temperate North America), Lemna minuta (widespread across southern U.S.), Lemna obscura (eastern-southeastern U.S.), Lemna perpusilla (eastern U.S.), Lemna trisulca (widespread temperate and boreal, but not southeast U.S.), Lemna turionifera (widespread temperate and boreal, but not southeast U.S.), and Lemna valdiviana (southeast U.S., and spotty in the southwest U.S.). Other species present may include Spirodela polyrrhiza (widespread temperate U.S.), Landoltia punctata (southeastern U.S.), Azolla microphylla, Azolla filiculoides, Wolffiella lingulata (rare), Wolffiella oblonga (extreme southwest and southeast U.S.), Wolffiella gladiata (southeast coastal plain), Wolffia brasiliensis (eastern temperate U.S.), Wolffia borealis (west coast temperate and eastern temperate U.S., but not coastal plain), Wolffia globosa (eastern temperate U.S.), and Wolffia columbiana (eastern temperate U.S.), as well as Riccia spp. (aquatic liverworts). Associated rooted floating aquatics include Potamogeton spp., Sagittaria spp., or Polygonum spp. may also be present s. While these latter species are rooted submerged species, and technically not part of the strictly floating community, they do intermingle. Biomass can be abundant under eutrophic conditions.

Diagnostic Characteristics: No Data Available

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: This is a broadly defined type. Although duckweed pond certainly occur widely across the region, it is not clear whether it is a helpful diagnostic species for pond classification. It is possible that a coastal plain Lemna association could be recognized based on the restricted distribution of many Lemna spp. Lemna and other characteristic wetland taxa that comprise floating, submerged and aquatic rooted associations are not well-reported in the literature, but they are known to occur in the field. Lemna and Azolla will be easy to distinguish from each other; some Lemna taxa may be less easy to distinguish from Spirodela, Wolffiella, and Wolffia.

Similar NVC Types: No Data Available

note: No Data Available