Lesser pondweed is a superficially grasslike herb producing a very slender, branching, somewhat compressed stem, usually less than 70 cm but occasionally up to one metre in length.

[7] These are quite morphologically variable plants, often with wide geographical and ecological ranges, which has resulted in a great deal of taxonomic confusion and an unusually large number of synonyms and invalid names (see the taxon box).

[10][1] Lesser pondweed grows in standing or slow-flowing water bodies such as ponds, lakes, ditches, slow-moving streams, and river backwaters.

It is a lowland plant and requires calcareous water, with a marked preference for high nutrient levels, and may form extensive beds in favourable situations, growing with other nutrient-tolerant species such as Myriophyllum spicatum and Zannichellia palustris.

It is tolerant of turbid water and is a good colonist, often exploiting temporary or disturbed habitats such as livestock drinking ponds, canals and ditches.

Globally, Potamogeton pusillus is listed as Least Concern.There is no evidence of local declines and in many areas it is probably increasing due to eutrophication of freshwater habitats.