202 HERRE 



Practically always sterile with us. But I very doubtfully refer 



here a densely sorediate and rather degenerate form on old fences at 



Santa Cruz, which has small to medium apothecia, with chestnut 



disks; margin entire to sub-crenulate, thick, and more or less sore- 



7 ~ 9 

 diose; spores ellipsoid, . /'. 



Not rare on twigs and branches of trees along the summit of the 

 range; also occurring on stones and shrubs about the entrance to 

 San Francisco Bay; on rocks in the San Bruno Hills; rarely on old 

 fences in the mountains. 



A common bark lichen throughout both the north and the south 

 temperate zones, but rarely fruiting. 



14. PARHELIA SOREDICA Nyl. 



Parwe/ia 50fe(^ica Nylander, Flora, 68: 605, 1885. Saskatchewan. 

 Parmelia soredica Herre, Proc. Wash. Acad. Sci. 7: 358. 1906. 

 Parmelia caperata Tuck. Syn. N. Am. Lich. I: 64. 1882. in part. 



Thallus coriaceous, large to very large, orbicular, becoming irreg- 

 ular, undulate, radiately plicate, closely adherent to the substratum; 

 lobes rounded, complicate, imbricate, their margins ascendant and 

 confluently white sorediate, except on periphery, where they are 

 dilated, smooth or wrinkled, with crenate edges. Surface of lobes 

 more or less sorediate; central portion of thallus finally passing into 

 sorediate heaps which become detached and fall away, leaving the 

 outer portions to continue their growth; color green to yellowish 

 green; beneath black with brown margin; outer lobes sometimes 

 with a few white or dark fibrils, otherwise naked ; KOH — ; medulla 

 and soredia red with CaCl202. 



Apothecia abundant on large specimens, generally of small or 

 medium size; disk chestnut; margin entire or lobulate, usually sore- 

 diate ; spores ellipsoid, -j ,"• 



On trees, fences, and roofs; perhaps occasional on rocks. Com- 

 mon everywhere in the valleys and foothills and extending to the 

 summit of the range; especially conspicuous and well grown on 

 Quercus lohala on whose rough bark it seems to attain its maximum 

 development. 



