THE LICHEN FLORA OF THE SANTA CRUZ PENINSULA 139 



rocks. Some species always sterile in temperate regions and often 

 difficult to determine. 



KEY TO SPECIES. 



A. On trees. 

 B. Dark green to black; smooth beneath; thallus fenestrate, wrinkled, 



ridged, isidiose i. chloromelum stellans 



BB. Lead-color to blackish green. 



C. Beneath fleecy with long white or brown fibrils ... 2. hildebrandii 

 CC. Beneath covered withminute velvety pubescence. 3. saturninum 

 A A. On earth, moss, or rocks. 



D. On limestone only; thallus thick, plicate, orbiculate .... 4. plicatile 

 DD. Not on limestone. 

 E. Thallus small to minute. 



F. Thallus small, foliaceous, rather entire 5. scotinum 



FF. Thallus minute or microscopically foliaceous to crustose. 



G. Thallus irregularly cut and divided 6. tenuissimum 



GG. Thallus chaffy or scurfy, areolate, wine-red with I. 



- 7. rhy par odes 



EE. Thallus medium size to large. 

 H. Thallus red-brown, chestnut, or lead-color; lobes narrowed 



with erect corniculate tips 8. palmatum 



HH. Color black. 



7. Lobes erect, crenate, narrowed, complicate. . .9. californicum 

 II. Thallus flat, expanded, more or less orbicular. . .lo/platynum 



i. LEPTOGIUM CHLOROMELUM STELLANS Tuck. 



Lichen chloromelos Swartz, Fl. Ind. Occident. 3: 1892. 1806. 

 Leptogium chloromelum Nyl. Syn. Meth. Lich. 1: 128. 1860. 

 Leptogium chloromelum stellans Tuck. Syn. N. Am. Lich. I: 163. 



1882. 

 Leptogium chloromelum stellans Herre, Proc. Wash. Acad. Sci. 7 : 382. 



1906. 



Thallus orbicular, becoming indeterminate, medium to very large, 

 more or less fenestrate, laciniate; lobes usually narrow, irregular, 

 more or less imbricate or coalescing; surface striate, wrinkled and 

 ridged, the ridges densely covered with black isidiose granules, or by 

 cristate-lacerate isidiose lobules; color dark green, plumbeous, or 

 black; beneath paler, wrinkled; rarely a very minute down sparingly 

 present. 



Sterile. 



Common on trees; reaching its maximum development at an alti- 

 tude of from 500 to 800 feet, the loosely connected thallus often 4 or 

 5 inches in diameter. 



Proc. Wash. Acad. Sci., May, 1910. 



