Hypogymnia is a genus of foliose lichens in the family Parmeliaceae. They are commonly known as tube lichens, bone lichens, or pillow lichens. Most species lack rhizines (root-like attachment organs on the lower surface) that are otherwise common in members of the Parmeliaceae, and have swollen lobes that are usually hollow. The lichens usually grow on the bark and wood of coniferous trees.