The water soldier grows typically in slow-moving meso-eutrophic waters which have a favourable level of free-iron in the sediment.
In autumn it sinks to hibernate as a rosette with green leaves on the sediment surface. The plants become buoyant in spring following increased photosynthetic gas production and the formation of new leaves.
The apical and sub-apical parts of the long roots are covered with root hairs and penetrate the sediment.
Female plants predominate in most of Europe with isolated male plants found in Denmark, Sweden and Finland.
Although fruits may form, no viable seed has been found in the British Isles since the Pleistocene. It reproduces vigorously via asexual reproduction.