Cetraria is a genus of fruticose lichens that associate with green algae as photobionts. Most species are found at high latitudes, occurring on sand or heath. Species have a characteristic "strap-like" form, with spiny lobe edges. Cetraria islandica, Iceland moss, is one of the few culinary lichens, ground and eaten by Northern Europeans in times of famine. Another species is used today as a "bulking" agent in garam masala of traditional Indian cuisine.