Lobaria is a genus of lichens commonly known as "lungwort" or "lung moss" as their physical shape somewhat resembles a lung. Lobaria species are unusual in that they have a three-part symbiosis, containing a fungus, an alga and a cyanobacterium, the presence of the cyanobacterium allowing nitrogen fixation. Their sensitivity to toxins makes them an excellent indicator of ecosystem health, and they are often found in ecological climax communities such as the old growth forests of northwestern North America.