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the somewhat similar Parmelia physodes (Group 5), which has a 

 black under surface, brown at the tips. Cetraria placorodia (Group 

 5), though whitish beneath, has no soredia, nor widely spreading 

 hairs, while its upper surface glistens slightly. Parmelia anibigua is 

 tinted with yellow and has a black under surface. Physcia sorediata 

 differs in its darker color, dark under surface, and touching parts. 

 P. obscitra and P. caesia are dark beneath, with dark holdfasts. 

 The only species of Physcia which requires study to distinguish 

 from P. speciosa is its own subspecies P. hypoleuca, which has 

 blackening holdfasts and a peculiar under surface, but is often 

 otherwise similar. P. astroidea, a smaller lichen, has its soredia 

 massed in the center. 



Physcia hypoleuca. Fig Lichen 



Also called P. speciosa var. hypoleuca or Anaptychia hypoleuca. 

 Found on trees and sometimes on rocks, fairly frequent on lime- 

 stone. The rosettes, up to 10 cm. across, with parts 3 or 4 mm. wide, 

 have a rampant, lumpy habit, with long, gracefully curving branches, 

 the tips somewhat lifted. Warts and tiny lobes occur scattered along 

 the margins, or may cover most of the lichen. The upper surface 

 is pale gray or whitish, the under surface very white or buff, with 

 blackening holdfasts. A vertical section shows under the microscope 

 that the normal lower layer of cells is missing near the tips, and the 

 under surface is really exposed pith, with a marked silky appear- 

 ance. 



Fruits not common, often somewhat fig-shaped, the deeply con- 

 cave spore surface dark brown, the thick, incurved rim often 

 bordered with tiny lobes, which may radiate from it, or grow in- 

 ward, partly hiding the disk. Spores 2-celled, blackish, 25 to 38 by 

 14 to 20 microns. 



Physcia hypoleuca differs from P. speciosa in the less frequent 

 marginal soredia, and the presence of tiny lobes and warts. Also 

 the holdfasts turn dark. From this and other species which re- 

 semble it, the bare pith beneath the tips is sufficient distinction, but 

 this character requires experience to detect. The presence of lobes 

 on the fruit-rim is another unusual character, shared by P. aqiiila 

 and P. pulvendenta in this group. P. aqiiila is typically brownish, 

 turning green when moist, and the under surface and holdfasts are 



