174 



not be confused with the bright yellow and orange tints of the much 

 smaller lichens in Group 9. 



Parmelia perlata. Broad Shield Lichen 



Seen occasionally in the highlands, particularly on rocks, where 

 it stands out by the breadth of its lifted lobes, often 2 or 3 cm. 

 across, and rising 1 cm. from the foothold. It spreads in crumpled 

 sheets rather than by trunks and branches, and may be 20 cm.- 

 across or more. The upper surface is smooth, pale greenish gray, 

 the margins often thickened by masses of whitish soredia. The 

 under surface is black, shining brown near the margins, smooth, 

 or with a very few black, root-like holdfasts. 



Fruits are rather rare, up to 12 mm. across, saucer-shape, 

 chestnut-brown, with a thick, smooth rim. Spores undivided, 

 colorless, 10 to 17 by 6 to 10 microns. 



Parmelia perlata' is not too easily determined, yet the real 

 species with which it can be confused are few. It resembles the 

 somewhat smaller Cetraria glauca (Group 4), which, however, has 

 frequent coral-like growths on the often torn and jagged margins, 

 and shows a net-like pattern of pits and wrinkles on the upper 

 surface. Sticta amplissima and 5^. pulmonaria (Group 7) are pale 

 and felted beneath. The only other lichen of similar color with 

 wide, lifted tips is P. perforata, including its subspecies, with black 

 hairs along the margin. Some botanists have allotted a few marginal 

 hairs to P. perlata, but Tuckerman follows the older lichenists in 

 insisting that P. perlata has no marginal hairs, and thus we have a 

 simple means of differentiating the two species. 



Parmelia perforata. Ragged Shield Lichen 



On the bark of trees in swamps and bogs, often high up, out 

 of reach, sometimes on rocks, not common, but to be met through- 

 out the New York area. Though not usually forming large rosettes, 

 it is conspicuous for its wide lobes with ragged and fringed mar- 

 gins. The tufts are irregular in shape, often 15 cm. across, with 

 no clearly radiating trunks or definite branches. The tips rise as 

 much as 2 cm. clear of the foothold, and bear conspicuous black 

 hairs along their crinkled margins. The upper surface is smooth, 

 greenish gray or pale olive, the under surface typically black, 

 wrinkled, covered in places with large, black, root-like holdfasts. 



