The Cumberland Rock Shield Lichen is a grey to green lichen which is found across much of North and South America. It can be found in all the Pacific Northwest. It is a relatively large lichen and grows on rocks, where it is tightly attached and impossible to remove. They can grow to 30 cm across the colonies can be of various shapes. The lichen is divided into deep irregular shapes near the center and often have a black edge. The underside of the lichen is a light brown color.
The cup shaped fruiting bodies are known as apothecia, and are present on short stalks on the surface of the lichen. The apothecia are up to 10 mm in diameter and often have toothed edges on the outside edge of the cups. Pycnidia, which are asexual reproductive organs, are also common on the lichen that look like small, flask shaped structures on the surface of the lichen body, which produce single cells as part of asexual reproduction. The pycnidia are very small and are visible as tiny black dots.
While Cumberland Rock Shield is widespread throughout the Pacific Northwest and all of BC. It prefers to grow upon partly submerged rock. Boulders and smaller rocks close to the waters edge seem to be its main habitat.