Encyclopædia Britannica, Ninth Edition/Iceland Moss

ICELAND MOSS, a lichen, Cetraria islandica (Achar.), whose erect or ascending foliaceous habit gives it something of the appearance of a moss, whence probably the name. The thallus has a pale chestnut colour, and grows to a height of from 3 to 4 inches, the branches being channelled or rolled into tubes, which terminate in flattened lobes with fringed edges. It grows abundantly in the mountainous regions of northern countries, and specially it is characteristic of the lava slopes and plains of the west and north of Iceland. As met with in commerce it is a light-grey harsh cartilaginous body, almost destitute of odour, and having a slightly bitter taste. It contains about 70 per cent. of lichenin or lichen-starch, a body isomeric with common starch, but wanting any appearance of structure. It also yields a peculiar modification of chlorophyll, called thallochlor, fumaric acid, licheno-stearic acid, and cetraric acid, to which last it owes its bitter taste. In medicine it is used as a mild tonic, and at the same time it forms a nutritious and easily digested amylaceous food, being used in place of starch in some preparations of cocoa. It is not, however, in great request, and even in Iceland it is only habitually resorted to in seasons of scarcity.