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cling to the rock instead of being crowded upward. The mounds of 

 powdery soredia, less than 0.5 mm. across, are centered on the 

 branches rather than on their margins. In some cases there are 

 spaces between the parts. The pith is white, not yellow. 



Fruits very rare, up to 0.8 mm. in diameter, black. Spores 

 brown, 2-celled, 14 to 20 by 5 to 7 microns. 



Physcia Frostii, one of the smallest of the Papery Lichens, sug- 

 gests the intermediate forms in Group 14, verging on the Crust 

 Lichens. It could be mistaken for the very common Crocynia sonata 

 (Group 14), which has a darker, often blackish center, and two or 

 three conspicuous zones of pale tips. Lecanora muralis (Group 14) 

 is colored like Physcia Frostii, but has much shorter, broader lobes, 

 with lifted margins, and bears many pale buff fruits. P. tribacia has 

 lifted tips, white beneath, while the tips of P. Frostii cling closely, 

 and are black beneath. P. teretiuscula is smaller, with even narrower 

 and separated parts, tapering to pointed tips, and has minute 

 soredia, while the soredia on P. Frostii are comparatively large 

 heaps. Rinodina oreina (Group 14), though of like habit, and with 

 similar spores, is much darker, distinctly greenish, without soredia, 

 and with frequent blackish fruits. 



Physcia speciosa. Plume Lichen 



Also called Anaptychia speciosa. Frequent on tree bark and 

 mossy ledges in open woods throughout the New York area. It 

 forms rosettes up to 10 cm. and more across, made up of graceful 

 branches with feathery divisions, the parts of rather uniform width, 

 1 mm. or more, the tips slightly lifted. The upper surface is greenish 

 to ashy gray or almost white. The upward-curling margins break 

 into pale blue or white, dusty soredia, which are often crescent- 

 shape, accenting the pattern of the lobes. The under surface is white, 

 with whitish holdfasts some of which might be considered marginal 

 hairs, which spread as much as 2 mm., often plainly visible from 

 above. 



Fruits are rare, brown, cup-shaped, up to 7 mm. in diameter. 

 Spores 2-celled, brown, 22 to 34 by 12 to 15 microns. 



Though not often seen in fruit, Physcia speciosa will be recog- 

 nized at once by its graceful branches edged with pale blue dust, 

 and the spreading white hairs below. It is easily distinguished from 



