138 



THE BOOK OF NATURE STUDY 



Evernia pmnastri forms drooping tufts of strap-like branches, 

 and rarely produces fruits. The thin branches show a net- 

 work of wrinkles, and the under side is much lighter in colour 

 (usually almost pure white) than the upper. Both of these 

 plants are often covered with a powder of soredes. 



Usnea and Evernia are 

 attached to the tree bark 

 or rocks at only one point, 

 but in the genus Clodonia, 

 to which the ' 'cup mosses ' ' 

 or " trumpet - mosses " 

 belong, we get some in- 

 dication of a flat lower 

 portion which creeps over 

 the substratum and bears 

 the erect branches. The 

 thin, flat, creeping part 

 growing over the soil or 

 on mosses, or on the bases 

 of tree trunks, is greyish- 

 green, while the erect 

 parts are cylindrical. In 

 many cases there is a 

 stalked cup which bears 

 soredes and spore fruits. 

 The most conspicuous of 

 our Cladonias is the "red 

 cup-moss "or "matches/' 

 in which the edges of the 

 cup bear large scarlet 

 fruits. The common 

 " trumpet-moss " has 

 brown fruits. In other kinds the erect organs are branched, and 

 in some cases there are no cups at all. This is shown in the 

 "reindeer-moss/' which is very common on our heaths and hills. 

 In Norway and the northern parts of Russia and Siberia it 

 grows in great abundance, often covering vast tracts, and giving 

 the landscape a yellowish-grey tint. It forms the chief food of 



FlG. 39." Reindeer Moss " Lichen (Cladonia 

 rangiferind). 



