Iceland Moss (cetraria Islandica, Acha-rius), a lichen common in the north of Europe and America. It consists of a tuft of deeply divided and dentate-ciliate margined, leaf-like, cartilaginous fronds, flattened out and of a lighter color at their base, but above incurved at their edges, so as to render them channelled; in general color they are of a dark olive brown. The fruit (apothecia) is borne upon the extremities and sides of the broadest branches, and is very broad and flat with elevated borders. This fruitful condition is only to be met with in the alpine regions of our northern mountains; when the plants occur upon the lower hills, and more especially in dry exposed pastures, they are uniformly infertile. It is possible that these last mentioned forms may yet prove to be distinct species; to settle this point, the occurrence of the apothecia is very desirable. A very bitter principle is resident in the alpine forms as well as in the Iceland moss of the shops; but this is almost wanting in the campestral sorts.
As an alleviative to pulmonary complaints the Iceland moss is well known; the principal part of the stock used in medicine is brought from Iceland and Norway. After the intense bitterness, which readily yields to cold water, has been extracted, boiling water is to be poured upon the mass, when, by keeping up a considerable heat and by several hours' steeping, an abundant and soothing mucilage is given out, and can be used with freedom, the drink being made palatable with a little sugar. Hooker says that after being purged of its bitterness the lichen "is dried, reduced to powder, and made into a cake or boiled and eaten with milk, and eaten with thankfulness too, by the poor natives" of those countries where it grows abundantly, "who consider that the very stones yield them bread." The mucilaginous character is owing to a great abundance of lichen starch. Even the bitter principle is tonic and useful in the treatment of disease. Similar alimentary substances are found in other lichens, resulting from the presence of this kind of starch.
Iceland Moss (Cetraria Islandica).