106 



DOMESTIC BOTANY. 



They turn black when dried, and contain a bitter principle. 

 I They have been of great utility as food to distressed Arctic 

 navigators. 



Lung Lichen (^Sticta pulmonaria). A broad leafy species, 

 growing on the ground in woods, generally among grass, and 

 called by the English peasants the " Lungs of the Oak." It 

 is used as a substitute for Iceland moss. 



Peltidea ajjJithosa, P. canina, and F. rufescens^ are similar 

 in habit and qualities to the last. 



Reindeer Moss [Cladoma rangiferina). An erect, finely- 

 branched species, of a white or grey colour, growing in com- 

 pact masses, about six inches high, and covering large tracts 

 of country throughout Northern Europe and Arctic America, 

 where it may be said to represent the herbage of more 

 southern latitudes. It is well known as the food of the reindeer. 



Tree hair (Usnea harhata and Alectoria juhata). Fila- 

 mentous lichens, growing in tufts on trees, and hanging 

 down from the branches like bunches of thread or grey hair. 

 They are common in this country, especially in damp woods, 

 often quite covering the trees; while in Lapland they are so 

 abundant as to give the fir forests quite a thick, gloomy ap- 

 pearance. 



Orchil {Roccella tinctorid). A foliaceous species growing 

 in tufts on rocks. It is from two to six inches high, and 

 differs much in breadth, which has led to several of the more 

 distinct forms being regarded as species. It is found in all 

 parts of the world, even on the dry rocks of Aden, and is 

 abundant on the rocky shores of this country, often growing 

 on perpendicular cliffs, from which situation it is collected, 

 men being lowered with ropes, for that purpose. It has been 

 extensively used in dyeing, and originally formed a valuable 

 article of commerce, but like many other things of the past, 

 lichen dyes are now being superseded by fine dyes obtained 

 from coal-tar. The delicate chemical test called " litmus" 

 is obtained from this, and other lichens. 



Many other lichens resembling the Roccella in habit, but 

 growing on trees, are found in this country. Ramalina 



