LICHENS OF THE STATE OF WASHINGTON 73 



6. Rhisocarpon grande (Flk.) Arn. Flora 54:149. 1871. 



Lecidea petraea var. fuscoatra f. grandis Flk. in Fw. Flora 11 :690. 1828. 

 Buellia petraea var. grandis (Flk.) Tuck. 



Thallus deep violet-gray (R) or brown with a purplish tinge, determi- 

 nate, thin to moderately thick, areoles small, convex, scattered on a promi- 

 nent black hypothallus. Apothecia 0.4-1.0 mm. in diameter; disk black, 

 convex to subglobose; proper margin black, thin, soon disappearing; 

 hypothecium dark brown; paraphyses coherent, tips brownish or bluish 

 black ; asci 8-spored ; spores hyaline to brown, oblong-ellipsoid, muriform, 

 26.4-40.0 X 13.2-16.5 fx. 



On rocks: Yakima Co.: gulch near Naches, 1350 ft., 1940, 3191. 

 Chelan Co.: butte near Chelan, 2000 ft., 1931, 1343a. Ferry Co.: San- 

 poil, 2000 ft., 1940, 3128; Laurier, 1644 ft., 1931, 1445a. Stevens Co.: 

 Boyds, 1470 ft., 1931, 1452. Spokane Co. : west of Spokane, 1950 ft., 1940, 

 2750. 



This species is common east of the Cascades. It resembles R. petraeum, 

 but can be separated from that species by the characteristic violet or purple 

 tinge of the thallus. 



7. Rhizocarpon petraeum (Wulf.) Mass. Ricerch. Auton. Lich. 102. 1852. 

 Lichen petraeus Wulf. Schrift. Gesellsch. nat. Freund. Berlin, 3:89. 



1787. 

 Buellia petraea var. vulgaris Tuck. Gen. Lich. 190. 1872. 



Thallus grayish white, gray, or brown, determinate, thin, smooth or 

 warty, sometimes areolate; areoles continuous or scattered on a black 

 hypothallus which is often inconspicuous. Apothecia circulai or angular, 

 crowded, 0.3-1.0 mm. in diameter, immersed or adnate; disk black or 

 brownish black, flat or convex ; proper margin black, thick, elevated, entire 

 or irregular, sometimes white pruinose; hypothecium dark brown; para- 

 physes somewhat distinct ; asci 8-spored ; spores hyaline or brown, oblong- 

 ellipsoid, muriform, 18.0-39.0 x 8.0-18.0 ix. 



On rocks and more rarely on old wood: Okanogan Co.: gulch near 

 Tonasket, 1200 ft., 1931, 1387. 



