Callitriche

There are round 25 species of water starwort and these are found growing in many places across the world. Many species make carpets that sit on the water surface, some having small leaves, others foliage that bears a visual resemblance to a feather. It can make mats that preclude sunlight, thus making cool retreats for the pond's inhabitants as well as providing a haven for aquatic insects. The two species most commonly encountered are Callitriche palustris and the native Callitriche stagnalis that is often used as an oxygenator. The flowers of the starwort are scarcely noticeable. The name refers to the starry appearance of close-packed foliage in some forms.