96 



with lobes but little divided, and less than 5 mm. wide. The 

 margins usually rise above the foothold to a height of less than 

 5 mm. It is seen commonly on rocks in the highlands of New 

 England, New York and New Jersey, but also grows on trees. 

 It does not fruit, though intermediate forms may. The import- 

 ant characters are the yellow under surface and yellow soredia. 

 Except for the close relationship with C. juniperina from 

 which perhaps it need be separated only in order to make recog- 

 nition easier, Cetraria pinastri is not likely to be confused with 

 other lichens. C. Oakesiana, resembling it somewhat, has pale 

 green, not yellow soredia, and a brown under surface. C. aures- 

 cens is white beneath, and without soredia. Parmelia amhigua, 

 P. centrifuga, P. incurva, and the larger P. conspersa and P. 

 caperata (Group 6), with Candelaria concolor and other spe- 

 cies of Group 9, though all yellow or yellowish on the upper sur- 

 face, are never yellow on the under. 



Cetraria Oakesiana. Oakes Shield Lichen. 



Throughout the highlands and pine barrens, this species will 

 be met in many localities, but not too plentifully, on trees and 

 rocks. Once learned, it is easy to recognize, yet at first each 

 point of the description must be checked carefully. Its trough- 

 like branches, usually about 5 mm. wide, spread irregularly side 

 by side, not forming symmetrical rosettes, but rarely over-lap- 

 ping. They usually rest on the foothold, but their margins curl 

 away from it 2 or 3 mm., and are waved and crinkled, though 

 not much lobed, often foaming into a pale green dust of soredia, 

 fading later to whitish. The upper surface is smooth, or only 

 slightly wrinkled, pale grayish green, the under surface light 

 brown, with a few brownish holdfasts sometimes visible. 



Except in the high mountains, and then rarely, it does not 

 fruit. Fruits dark brown, up to 6 mm. across. Spores undivided, 

 colorless, 5 to 10 by 4 to 6 microns. 



The pale green soredia distinguish it from other Papery 

 Lichens, but when these have faded or are wanting, the general 

 habit, curling margins, and light brown under surface must be 

 noted. It will be found in association with Cetraria ciliaris and 

 C. lacunosa (Group 4), which i^ise high above the foothold, and 

 with many species of Parmelia, none of which are trough-shaped. 

 Physcia speciosa and P. sorediata (Group 8) often have colored 

 soredia, but pale blue, not green. 



