THE LICHEN FLORA OF THE SANTA CRUZ PENINSULA 135 



Thallus small or medium size, circular, irregularly lobed, with 

 crenate margin; marked by thick, rough, anastomosing ridges 

 densely covered by black granules; more or less fenestrate; color 

 dark green or black; beneath pale, smooth, much wrinkled and pitted. 



Apothecia numerous, mostly on the ridges; disk from concave 

 becoming flat or even convex; reddish or darkening; margin entire; 



spores spindle-shaped, long, plurilocular, /*. 



45 ~ 75 



On trees and not rare in the foothills. Found all over the north 

 temperate zone. 



2. COLLEMA VESPERTILIO (Lightf.) Wainio. 



Lichen vesper tilio Lightf oot, Flora Scotica, 2: 840. 1777. 

 Collema vespertilio Wainio, Act. Soc. Faun. Fl.Fennic. 7: 235. 1890. 

 Collema vespertilio Herre, Proc. Wash. Acad. Sci. 7: 376. 1906. 



Thallus of medium size, orbicular, thin, closely appressed; lobe, 

 rounded, with entire or crenate margin; surface naked, smooths 

 radiately wrinkled and thickly pustulate; color yellow-green, very 

 dark green, and black; beneath paler or concolorous, lacunose or 

 pitted. 



Apothecia small, usually very numerous and crowded; disk red- 

 dish or blackening; plane, becoming convex; spores needle-shaped or 



spindle-like, long, plurilocular, /*. 



47-5 ~ 55 



On trees and perhaps occasionally on rocks. Common in the foot- 

 hills at moderate elevations. Our most abundant Collema. 



Confused by most writers with nigrescens, its distribution there- 

 fore uncertain, but probably general in all temperate regions. 



3. COLLEMA NIGRESCENS (Leers.) Wainio. 



Lichen nigrescens Hudson, Flora Anglica, 450. 1762 (?). 

 Lichen nigrescens Leers. Fl. Herborn. 945. 1775. 

 Collema nigrescens Wainio, Act. Soc. Faun. Fl. Fenn. 7: 235. 1890. 

 Collema nigrescens Tuck. Syn. N. Am. Lich. I: 147. 1882. in part. 

 Collema nigrescens Herre, Proc. Wash. Acad. Sci. 7: 376. 1906. 

 Thallus of medium size, more or less orbiculate, thin, marginally 

 closely appressed, the rounded lobes with margins more or less undu- 



