NEW ENGLAND LICHENS An 



ally darkening centrally; old examples, especially those on 

 rock substata, have only the periphery pale green, darkening 

 centrally to often a very dark green or almost black. The 

 lobes of the thallus are large, imbricate, and rounded, sub- 

 lobed, and round-toothed. The central portion of the thallus 

 is irregularly folded and wrinkled, the crest of the folds, in 

 fully developed examples, from partially to entirely soredi- 

 ate, finally reaching a conglomerate crust of usually, white or 

 pale green soredia, rarely darkened to the color of the 

 thallus. The remainder of the thallus is often sparingly 

 sprinkled with soredia as well. 



Beneath the thallus is black, slightly wrinkled, and 

 largely covered, except at the periphery, which is dark- 

 glossy brown, with a black, often crustose nap of rhizoids. 

 The central, white medullary layer is sometimes exposed in 

 removing specimens from the substratum. 



The apothecia (see Fig. 2) are rare, (the ratio of plants 

 bearing them, exceeding small) generally poorly developed, 

 and often easily over-looked, occuring as a rule in rock grow- 

 ing examples. They appear first as seemingly circularly 

 arranged soredia, not more than a millimeter in diameter, 

 between the folds of the thallus, the darii brown epithecium 

 hardly visible. The largest apothecium of New England 

 examples that I have examined is eight millimeters* in dia- 

 ameter. They are generally irregular in shape, finally 

 grouped, with sorediate or isidoid, inturned margins, which 

 are finally destroyed, exposing plainly the chestnut-brown 

 epithecium. The spores are simple, without color, elliptical, 

 measuring from 15 to 25 by 7-10 micromillimeters. 



Substratum. Parmelia caperata occurs on living conif- 

 erous and deciduous growths, rocks, walls, unpainted build- 

 ings, fences, rarely primarily on decaying vegetation. It is 

 a tree loving species, occuring commonly on fences, and 



i*, 



* Specimen from Vermont, collected by C. G. Pringle, Sprague 

 Herbarium, Boston Society Natural History. (See Fig. 2.) 



