The water soldier is dioecious, having separate male and female plants.

It is perennial and is usually floating and partially emergent in summer and submerged in winter.
Roots are simple and rarely attached to substrate

Stems are 

  • stoloniferous, short or form runners
  • with complex branching

Branches are runner-like bearing terminal buds which function as protective cases, hibernacula.

Leaves are basal, rigid and brittle, sessile, narrowly triangular to linear and tapered towards the apex spinous-serrate.

Spathes consist of two free, overlapping, conduplicate, spinous-serrate bracts.
The male inflorescence has 3--6 flowers. The female inflorescence has one or rarely two flowers

  • free
  • obovate
  • up to 29mm long
  • white
  • showy
  • evanescent
  • much larger than the sepals