364 HERRE 



Common on twigs and trunks throughout our range. Par- 

 ticularly well developed on y£sctiltcs californica^ above 2000 

 feet. Abundant on rocks along the summit of the range. 

 Lichen aipolius Ach. Lichenogr. Suec. Prodr. 112. 1798. 

 Physcia aipolia Nyl. Flora, 53 : 38. 1870. 



10. PHYSCIA TRIBACIA (Ach.) Tuckerman. 



Thallus more or less orbicular, usually rather small, much 

 lobed ; lobes short, intricatel}" laciniate ; their margins upturned, 

 much dissected, granulate, becoming lined with confluent 

 soredia ; center of thallus sometimes converted to a granulate 

 or sorediate crust ; color bluish white, gray, or ashy ; beneath 

 white, becoming buff centrally ; sparingly covered with short, 

 white fibrils. Apothecia not seen. 



On trees and rocks. 



Common in the lowlands and foothills, the best specimens on 

 sandstone. 



Lccanora tribac/a Ach. Lich. Univ. 4i5« 1810. 

 Physcia trihacia Tuck. Lich. Am. Sept. No. 85 ; Syn. N. 



Am. Lich. I : 75. 1882. 



11. PHYSCIA HISPIDA (Schreb.) Tuckerman. 



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

 commonly forming small, loose, diffuse clumps ; the short as- 

 cendant lobes irregularly and deeply cleft, their tips inflated 

 and vaulted, forming a very characteristic feature ; margins of 

 lobes beset with long, concolorous, or now darkening, fibrils ; 

 color white or bluish ashy gray ; beneath white, with few short 

 white fibrils. Sterile. 



Frequent on trees and slirubs throughout. Common in the 

 Stanford University arboretum on the stems of the giant cactus 

 of Arizona, Cereus gigantcus. 



Lichen hispidus Schreber, Spicil. Fl. Lips. 126. 177 1. 

 Physcia hispida Tuck., Obs. Lich. 397; Tuck. Syn. N. Am. 



Lich. I : 75. 1SS2. 



It seems to the author that this species should stand as Phy- 

 scia tenclla (Scop.) Nyl., when the synonymy should be as 

 follows : 



