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and often not much divided, with margins frequently breaking 

 into dusty white soredia or extended into coral-Hke growths. A 

 Httle of the under surface may be whitish near the tips, but it 

 is more Hkely to be shining brown there, jet black farther down. 

 Fruits much like C. lacunosa, but somewhat larger, and 

 without the hole in the center, occur very rarely. In their 

 absence, Cetraria glauca can be mistaken for Parmelia perlata 

 (Group 6), which also fruits rarely, but is of a darker color, 

 larger size, with broader, simpler lobes, which though often 

 margined with soredia, do not develop coral-like growths. P. 

 perlata is commonly found on rocks, C. glauca on trees. If any 

 marginal hairs are present, a lichen of this nature is almost 

 surely P. perforata, which grows on trees. (For distinctions 

 within this group, see C. ciliaris.) 



Cetraria saepincola. Chocolate Shield Lichen. 



This small species, rarely spreading more than 3 or 4 cm., 

 or rising more than 5 mm. from the twigs and tree-bark on 

 which it grows, has a characteristic chocolate brown color, 

 sometimes shading to olive green or blackish, especially when 

 wet, shared by few local lichens. It inhabits the Shawangunks 

 and mountain crests to the north. When well developed, it 

 forms loose, irregular, wrinkled tufts, like C. juniperina in mini- 

 ature, but is often reduced to a few fruits clustered on a twig, 

 almost no stalks or lobes visible. Even in larger forms, the lobes 

 are rather simple, smooth and not intertangled. The under sur- 

 face is paler brown. 



Fruits, up to 4 mm. across, usually plentiful, are chocolate 

 brown like the rest of the lichen, and seat tightly against the 

 upper margins, with a slightly toothed rim. Spores undivided, 

 colorless, 6 to 9 by 3 to 6 microns. 



C. fahlunensis, (Group 5), with similar color, but longer 

 lobes and few fruits, grows only on rocks. The only other brown 

 papery lichen of comparable size on local trees, is the rather 

 common Parmelia olivacea (Group 5) and its varieties or sub- 

 species, usually olive-brown or brassy, lying flat against the 

 bark, and seldom fruiting. It can be distinguished by its mostly 

 black under surface. The brown lichens in Group 7, Sticta, 

 Peltigera, Nephroma, and in Group 12, Umbilicaria and Derma- 

 tocarpon, are mostly much larger and wholly different lichens, 

 none of them with the chocolate shade. 



