THE LICHEN FLORA OF THE SANTA CRUZ PENINSULA 257 



marked with small tooth-like lobules; color varying from green 

 through buff to tawny brown; gray pruinose at least on tips of 

 lobes, but usually otherwise naked; beneath black and densely black 

 fibrillose, usually pale at margin; medullary layer white. 



Apothecia pruinose, sessile; disk flat, black, or reddish-black; 

 often gray or bluish pruinose; margin thick, entire, fringed with 



small thalline lobules; spores /*. 



27 - 32 



This species grows luxuriantly on oaks, principally Quercus chryso- 

 lepis, along the summit of the range at an altitude of 2200 feet and 

 above. 



5. PHYSCIA MUSCIGENA (Ach.) Nyl. 



Parmelia muscigena Ach. Lich. Univ. 472. 1810. 



Physcia muscigena Nyl. Syn. Meth. Lich. 1 : 418. 1860. 



Physcia muscigena Herre, Proc. Wash. Acad. Sci. 7: 363. 1906. 



Thallus diffuse, spreading, irregular; the laciniate, numerous lobes 

 short, narrow, distinct, often upturned at the tip; margins more or 

 less sorediate or powdery with confluent, sulfur-colored soredia; sur- 

 face often with isidiose or cephaloid outgrowths; medullary layer 

 usually greenish yellow or sulfur-colored; color of thallus brown, 

 finally a very dark dull brown; rarely greenish; usually only tips of 

 lobes pruinose; beneath white, becoming very dark; densely clothed 

 with more or less hispid black fibrils. 



Apothecia rare, scattered; margin thick, becoming sorediate; 



spores '3 -75 -i7. 5.^ 



27-5 - 37-5 



Common in the foothills on mossy sandstone and the trunks of 

 oaks. 



6. PHYSCIA STELLARIS (L.) Nyl. 



Lichen stellaris L. Sp. Plant. 2: 1144. 1753. 

 Physcia stellaris Nyl. Syn. Meth. Lich. 1 : 424. 1860. 

 Physcia stellaris Tuck. Syn. N. Am. Lich. I: 73. 1882. 

 Physcia stellaris Herre, Proc. Wash. Acad. Sci. 7: 363. 1906. 



Thallus smooth, appressed, stellate or irregular; lobes many cleft, 

 sinuate, very close together; thickly sprinkled with small white sub- 

 epidermal spots; neither pruinose nor sorediate; color white; beneath 



