NOVEMBER. 529 



P. venosa, and P. aphtliosa are very beautiful, but 

 these only occur in mountainous districts. 



Gyrophora and Umbilicaria have a very singular 

 appearance, and might almost be mistaken for large 

 flakes of soot, were it not for the central root by which 

 they are fixed to the rocks where they grow. The 

 QetraricB are northern or alpine plants, though the 

 glaucous Cetraria often adorns heaths and stony 

 places with its wide spreading glaucous-grey thalli, in 

 spots where the white-runiped Wheatear is sure to 

 be seen flitting about. Roccella is a maritime Lichen, 

 which yields a most valuable dye.* Borrera ciliaris 

 et tenella, Evernia prunastri, Hamalina farinacea, and 

 Usnea plicata et Jlorida, either together or in separate 

 divisions, form those hoary flakes, fringes, and pendent 

 floccy masses, which in winter and early spring give 

 such a spectral aspect to the branches of the trees 

 they clothe ;t as if nature had robed them with a 

 permanent hoar frost 



" There fibrous, floating in the air ; 

 Here hoary, curl'd, and light ; 

 Like tresses fine of maiden's hair, 

 Or hermit's lock of white." 



To some of these Lichens, more particularly, per- 



* Many of the crustaceous and foliaceous lichens might be used in 

 dyeing processes, but the Roccella or Orchell, brought from the Canary 

 islands, is most valued, and has been most employed. The price of this 

 in the market is now about ^290 per ton, and at particular times it has 

 risen to nearly ^1000 ! 



t This is an appearance noticed by many poets, but with a want of 

 botanical exactness, the grey lichens producing it are termed erroneously 

 Mosses thus Dr. DARWIN mentions 



" The moss-grown antlers of the aged oak ," 



and SOUTHEY, in a beautiful sonnet descriptive of Winter, makes the same 

 mistake " A wrinkled crabbed man they picture thee 

 Old Winter ! with a ragged beard as grey 

 As the long moss upon the apple tree. 1 " 



But this " long moss" is certainly the pendent lichen Usnea plicata. 



2M 



