CLOTHED WITH VEGETATION. 57 



granite they grow, with widening periphery, some lighter 

 and some darker in color. But there are nobler lichens 

 than these crustaceous kinds. Some, instead of being 

 pebbly, are scaly, and others even leafy in appearance. 

 One of these large leafy varieties was found last winter 

 (1896) which measured nine inches across the leaf. 



This one {Umbilicaria dilleiiii) was a brown leathery 

 pad with a black under surface fastened flat to the rock by 

 a short cord or umbilicus in the middle. They love damp- 

 ness and pure air, avoiding the smoke of cities and the 

 hot sunshine. The ledges of Cohasset which have a 

 northwest exposure were early sought out by these 

 humble plants where they might hang in pure air, being 

 bathed by drippings from above. They asked no food 

 from the rock, but only a j^lace to hang out. 



Some of the larger ones are probably the most vener- 

 able of all settlers ; for it is said that no lichen ever died 

 of old age, and it may be that some of these now living 

 could span a thousand years, so that no living thing about 

 them can rival them for antiquity. 



Some of the lichens of these later days take the lead 

 of all winter beauties. They are the brilliant red-orange 

 patches upon the bark of trees or upon the rocks. Hardly 

 an elm on our streets but has for its adornment this touch 

 of beauty, when colors are scarce and flowers have fled. 

 This red kind {JTheloscJiistes parietind) is contrasted often 

 upon the same tree trunk with a rich brown lichen 

 {Collcvid) and a gray lichen {Parnielia) and several other 

 varieties besides mosses, making a brilliant spectacle of 

 color even in winter. 



When the hot sun deprives lichens of their moisture 

 they close up their pores, according to their immemorial 

 custom, and wait for months if necessary until the drought 

 is ended and their nutriment comes again. 



In the early post-glacial times, when other plant life was 

 scarce, the lichens composed a larger proportion of the 



