Guide to the Lichens of the New York Area — Part 4* 



G. G. Xeakixg 



Group 6. The Larger Shield Lichens. IMats of paper-Hke struc- 

 ture growing close to the foothold, or the tips and margins rising 

 somewhat from it. Dividing into radiating trunks more or less 

 branching and lobed, or the central parts uniting in a confused 

 fabric, some of the branches or lobes usually broader than 5 mm. 

 Fruits brown, sometimes purplish or greenish. Spores undivided, 

 colorless. Algal cells not in chains. 



This group is distinguished from all other large Papery Lichens 

 by the undivided, colorless spores, but as many of the species 

 commonly fail to fruit, characters other than the spores must be 

 stressed. Foreign lichenists have attempted to substitute chemistry 

 for botany in separating the species of this and of other puzzling 

 groups. Since the two most noted American lichenists, Tuckerman 

 and Fink, have declined to recognize chemical determinations, we 

 may assume that the American tradition permits us to use the 

 botanical, thereby avoiding the added confusions which result 

 from chemical methods. 



Paniiclia sa.ratilis Stane-Raw 



A common tree-lichen, found in swamps, woods and highlands, 

 everywhere that lichens grow ; also seen at times on rocks. It forms 



* It is the aim of this Lichen Guide to enable those who have no special 

 knowledge of lichens, to identify the majority of the more common species, 

 and all the more conspicuous ones, without technical study and, if necessary, 

 without the use of a compound microscope. If it were possible to accom- 

 plish this by brief and concise keys, the detailed descriptions here would be 

 unnecessary. But if such keys could be written, it would not have remained 

 for me to write them. 



Therefore, as a substitute for the ordinary key, I have adopted a system 

 of grouping and cross-reference, to be used as follows : First decide whether 

 the lichen is Stalked (Groups 1 to 4), Papery (Groups 5 to 12), Flake 

 (Group 13) or Crust (Groups 14 and on). Then read the description of 

 each group head in that division, select the most likely group, and look over 

 the illustrations. If an illustration looks like the specimen, read the descrip- 

 tion, noting especially the comparisons which follow it. If the description 

 does not agree with the specimen, one of the species compared with it probablj'^ 

 will. This method, though inexact, will accomplish the purposes of a key, 

 and because the descriptions are given in repetitive detail, should prevent 

 wrong determinations. 



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