322 ECONOMIC BOTANY. 



326. Iceland Moss, Cetraria islandica, like the pre- 

 ceding, is a foliaceous Lichen, three or four inches high, 

 with branches channeled or rolled into a tube. It grows 

 in the mountains of the North, and is characteristic of the 

 lava slopes of Iceland. It contains seventy per cent, of 

 Lichenin, or Lichen-starch, a substance isomeric with 

 starch, but destitute of structure. It also contains cetraric 

 acid, which gives a bitter taste. It forms a nutritious and 

 easily-digested food, and is a mild tonic. In Iceland it is 

 used, however, as food only in times of scarcity. 



