95 



width of about 1 mm., with the tips a Httle wider or narrower. 

 Margins and tips are lifted a little, forming a shallow trough. 

 In some specimens, tiny, blackish granules border the older 

 parts. In the form seen in the Shawangunk and Kittatinny 

 Mountains, sometimes called var. Frostii, the margins are 

 dusted with whitish soredia. The upper surface is smooth, shin- 

 ing brown or dark olive at the tips, blackish on the older parts 

 or all bleached rather grayish. Under surface slightly paler, 

 with a few dark, root-like holdfasts. 



Fruits, seldom or never seen in the New York area, are un- 

 expectedly large, up to 1 cm, in diameter, and seated rather 

 tightly against the older trunks. Color dark brown. Rim smooth 

 or beaded. Spores undivided, colorless, 5 to 11 by 3 to 7 mi- 

 crons. 



Cetraria fahlunensis looks at first glance almost exactly like 

 Parmelia stygia, a northern lichen which hardly reaches the 

 New York area, and which has the trunks and branches slightly 

 convex instead of trough-shaped, the under surface being pitch- 

 black instead of brown. C. saepincola (Group 4), though of 

 nearly the same color, rises much higher from the foothold, 

 grows on trees and wood instead of rocks, and has plentiful, 

 much smaller fruits. Shining tips distinguish all these Shield 

 Lichens from the dull-surfaced Physcia aquila (Group 8) and 

 Pannaria microphylla (Group 10), both of which are brownish 

 in color. Perhaps Parmelia omphalodes , a strictly northern, 

 small, brown variety of P. saxatilis, should also be mentioned 

 here. It has wider and thinner parts than C . fahlunensis , the up- 

 per surface somewhat pitted, and the under densely clothed 

 with root-like holdfasts. It is rarely or never found in the New 

 York area, nor is P. sorediata, a form of P. stygia with round, 

 white soredia. 



Cetraria pinastri. Pine Lichen. 



Also called Cetraria juniperina var. pinastri. A form similar 

 to C. juniperina (Group 4) in color, yellowish to olive green on 

 the upper surface, yellow on the under, with the margins usu- 

 ally breaking into greenish yellow dust (soredia). Some consider 

 these soredia the determining character of C. pinastri, but 

 neither this view nor any other can explain satisfactorily the 

 intermediate forms. This lichen is typically small and straggling, 



