Callitriche marginata is a species of aquatic plant known by the common name winged water starwort. Callitriche marginata is native to the west coast of North America from British Columbia to Baja California, where it grows in and around vernal pools. It is secure in the southern part of its range in California and Baja, but is rare in Oregon, unknown in Washington, and known from only eight occurrences in British Columbia. In California, it is found from the Coast Ranges, Transverse Ranges, and Peninsular Ranges, through the Central Valley to the High Sierra Nevada.