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Cetraria aurescens. Yellowing Shield Lichen. 



A small, rather rare lichen described from New England 

 and New Jersey, growing on coniferous trees and old rails, and 

 to be looked for in the pine barrens. It looks something like a 

 pale, flat form of C. juniperina, with a wrinkled and warty up- 

 per surface pale yellowish green or yellowish gray, the under 

 surface whitish, with many whitish root-like holdfasts. Only the 

 crinkled margins and tips rise from the foothold. Its many 

 branches and lobes 2 or 3 mm. wide, rarely spread more than 4 

 or 5 cm. in an irregular pattern. 



Fruits are frequent, large in proportion, up to 7 mm. across, 

 and often mounted above the margins on spurs as much as 5 

 mm. high. The disk is chestnut-brown, the rim toothed. Spores 

 undivided, colorless, 3 to 6 by 3 to 5 microns. 



From C. juniperina, C. pinastri and C. Oakesiana, Cetraria 

 aurescens can be distinguished by the white under surface and 

 the absence of dusty soredia, from C. placorodia and Parmelia 

 amhigua by the crinkled and lifted margins. The spores also 

 are smaller than those of any local Shield Lichen except the 

 very difTerent Parmelia colpodes with swollen tips. 



Cetraria Fendleri. Fendler Shield Lichen. 



A rare lichen to be looked for on pine bark in the pine bar- 

 rens, where it often spreads only 1 or 2 cm., or is reduced to a 

 few mere wisps around crowded fruits. The typical color is 

 brownish olive, dull, not shining, with a white under surface. 

 The tips and margins are usually slightly raised and finely cut, 

 with small lobes ending in many delicate points which might 

 sometimes be considered marginal hairs. 



Fruits are many and often crowded, chestnut-brown, shin- 

 ing, smaller than 4 mm. in diameter, and with rims distinctly 

 toothed or notched, or even minutely lobed. Spores undivided, 

 colorless, 4 to 1 1 by 4 to 5 microns. 



Owing to its small size and dark coloring, Cetraria Fendleri 

 will easily escape observation. At a glance it looks somewhat like 

 the common Physcia endochrysea (Group 8) which is small and 

 olive-gray, but which, when scratched with the fingernail, re- 

 veals an internal blood-orange color. The finely divided and 

 pointed lobes of C. Fendleri distinguish it from all other brown 

 Papery Lichens. With it on the pine bark will be found the 

 flakes of Psora anlhracophila and P. ostreata (Group 13) and 



