Callitriche stagnalis is a species of aquatic plant known by the common names common water-starwort or pond water-starwort. It is native to Europe but it is present on other continents as an introduced species and sometimes a noxious weed of waterways. This is an annual herb rooting to the substrate in shallow water or in mud alongside water bodies. Slender stems reach to the surface and form floating mats of leaves, which are often round to spoon-shaped but are variable in morphology. The plants are monoecious, with male and female flowers on an individual. Both types of flower are very tiny and whitish in color.