A new green chlorococcoid alga, Echinocoleum flocculosum sp. nov., is described. It was collected from Stoney Lake. Kalamazoo County, and Miller's Marsh, Charlevoix County, Michigan, and in Kansas from a residual streambed pool near Fall River, Greenwood County, and a pond in an old oxbow depression at Lawrence, Douglas County. It is characterized by being a free floating single celled or immobile aggregate colony. Individual cells are spherical and contain a cup-shaped chloroplast with a single pyrenoid. All cells bear characteristic mucilage protuberances giving the cell an overall starshaped appearance.