THE LICHEN FLORA OF THE SANTA CRUZ PENINSULA 259 



bluish white, gray, or ashy; beneath white, becoming buff centrally; 

 sparingly covered with short white fibrils. 

 Apothecia rare, small to medium, sessile; disk brown to black; 



margin thick, entire or somewhat rugose; spores 5 /. 



Common in the foothills on trees and rocks. A common lichen of 

 Europe and North America. 



9. PHYSCIA TENELLA (Scop.) Nyl. 



Lichen tenellus Scopoli, Flor. Car. ed. 2, 2: 394. 1772. 

 Physcia tenella Nyl. Flora, 57: 306. 1874. 

 Physcia hispida Tuck. Syn. N. Am. Lich. I: 75. 1882. 

 Physcia hispida Herre, Proc. Wash. Acad. Sci. 7: 364. 1906. 



Thallus quite small; sub-stellate and appressed, or more com- 

 monly forming small, loose, diffuse clumps; the short ascendant 

 lobes irregularly and deeply cleft, their tips inflated and vaulted, 

 forming a very characteristic feature; margins of lobes beset with 

 long, concolorous, or occasionally darkening, fibrils; color white or 

 bluish ashy-gray; beneath white, with few short white fibrils. 



Sterile with us. 



Sometimes covering considerable areas, and dwarfed so as to be 

 scarcely recognizable. 



Frequent on trees and shrubs throughout. Occurs in the univer- 

 sity arboretum on stems of the giant cactus of Arizona, Cereus gigan- 

 teus. 



Common throughout the colder portions of the northern hemi- 

 sphere. 



10. PHYSCIA ADGLUTINATA (Flk.) Nyl. 



Lecanora adglutinata Floerke, Deutsch. Lich. 4: 7. 1815 . 

 Physcia adglutinata Nyl. Syn. Meth. Lich. 1 : 428. 1860. 

 Physcia adglutinata Tuck. Syn. N. Am. Lich. 1 : 77. 1882. 

 Physcia adglutinata Herre, Proc. Wash. Acad. Sci. 7: 365. 1906. 



Thallus small, inconspicuous; very closely appressed so that it 

 appears to be a part of the substratum; lobes thin, flat, coalescent; 

 center of the thallus often crustose; color "glaucescent becoming 

 cinerascent and brown, pale and scarcely fibrillose beneath; apothe- 



