Desmid, algae and sphagnum moss. Polarised light micrograph of Xanthidium antilopaeum (lower right) and Bambusina sp. (long, green) desmids with simple green algae (small, round) on Sphagnum sp. moss (background). Desmids are a common group of freshwater single-celled algae that have intricate cell walls. Micrasterias is highly adapted to nutrient poor, acidic water. Magnification: x200 when printed 10 centimetres wide.