510 



THE LICHEN FAMILY. 



Class IV.— THALLOGENS. 



CL VII.— THE LICHEN FAMILY. Lichenes. 



Lichens are plants composed entirely of cellular tissue, wrought 

 either into crisp and fringy tufts ; or into wiry branches resembling 

 locks of coarse grey hair, uncombed and dishevelled; or into thin 

 flat, dry, crustaceous or granulated plates, which spread horizontally, 

 and often resemble the withered leaves of trees. Some species are 



Fig. 226. 

 Cladonia rangiferina (enlarged). 



Fig. 227. 

 Stereocaulon paschale. 



little more than minute tubercles, and not a few are microscopic. The 

 largest, after the hair-like kinds, which often hang from the branches 

 of trees to a length of several feet, rarely exceed four or five inches in 

 height or breadth, and when of such diameter, they arc generally of 

 inconsiderable thickness. With a solitary exception, none live cither 

 in water or upon decaying matter, where they give way to Algoc and 

 Fungi ; they select, on the contrary, the most airy and unsheltered 

 situations, stern alpine solitudes, desolate cliffs by the sea, bleak 

 mountains, and wild and breezy moors. None grow in meadows and 



