46 



THE PLANT WORLD 



lichens common to New England; not because I feel my- 

 self possessed of any great knowledge of the plants, outside 

 the necessary results of the observance of them for a period 

 of years, but because I feel that no presentation of them, clear 

 at all, has ever been attempted so far as I am aware. 



I have tried to treat the present species, and shall the 

 future, in a scientific manner, presenting not so much the 

 observations of others, but the conclusions reached from my 

 own study of them. Lichens have been mainly studied from 

 a purely scientific and systematic point of view, i. e., the 

 naming of new forms, the determination of their exact place 

 in Nature; the former at least, after all, of little importance. 

 Little has been done or at least written, of their life histories 

 — and though much of what I write is known to others, it is 

 nowhere, so far as I know set down. 



Thoreau, when he philosophized thus, spoke for many of 

 us — "I knock the back of my hand against a rock, and as I 

 smooth back the skin I find myself prepared to study lichens 

 there" .... "I have almost a slight, dry headache as 

 the result of this observation. How to observe is how to 

 behave." .... "To crown, all lichens which are so 

 thin are described in the dry state, as they are most com- 

 monly, not most truly seen. They are indeed, dryly de- 

 scribed." 



PARMELIA CAPERATA (L.) Ach. 



Wrinkled Parmelia. "Stone Crottles." 



Synonomy: Lichen caperatus, Linn, sp. PL 1:1147. 



1753- 



Parmelia caperata, Ach. Meth. Lich. Pt. 11. 216. 1803. 



Imbricaria caperata (L.)De Cand, Fl, Fl. Gall. S |.. 

 1806. 



Description: (See Fig. i.) The thallus varies in 



specimens from strong membranaceous to coriaceous, some- 

 times reaching on rock substata a diameter of fourteen 

 inches. Rock examples develop the thinner, membranaceous 

 thallus, tree examples the coriaceous. In young specimens 

 the entire thallus above is pale green to sulphurous, occasion- 



