72 LICHENS OF THE STATE OF WASHINGTON 



Thallus creamy white or tawny, thin or moderately thick, warty or 

 cracked areolate, areoles unequal in size, continguous or scattered, reaction 

 with KOH yellow then red. Apothecia numerous, 0.2-0.5 mm. in diameter, 

 innate or subsessile ; disk black, flat to convex, slightly pruinose ; proper 

 margin grayish, finally disappearing ; hypothecium pale brown ; paraphyses 

 loose, with brown knob-like tips; asci 8-spored; spores grayish, oblong- 

 ellipsoid, 3-septate or muriform, 16.5-19.8 x 6.6-9.9 /*. 



On rocks: San Juan Co.: San Juan Island, Pt. Caution, 1928, 1947a. 



A very rare species, easily determined by the yellow and then red color 

 change with KOH. 



4. Rhisocarpon disporum (Naeg.) Miill. Arg. Revue Mycolog. 1:170. 

 1879. 

 Lecidea dispora Naeg. in Hepp, Flecht. Europ. No. 28. 1853. 



Thallus gray or brownish, indeterminate, areoles scattered or con- 

 tiguous, rather round, flat to convex, on an indistinct black hypothallus. 

 Apothecia circular, 0.5-0.8 mm. in diameter, sessile; disk black, flat to 

 slightly convex ; proper margin slightly elevated, entire, persistent ; hypo- 

 thecium dark brown ; paraphyses coherent, tips violaceous black, asci 1 or 2- 

 spored; spores hyaline at first, becoming brownish gray or dark brown, 

 oblong-ellipsoid, large, muriform, 26.4-60.0 x 13.2-30.0 fi. 



On rocks: Yakima Co.: gulch near Naches, 1350 ft., 1931, 1174, 

 Chelan Co.: Twisp Trail, 4000 ft., 1931, 1298. Okanogan Co.: gulch near 

 Tonasket, 1200 ft., 1931, 1383. 



5. Rhizocarpon geographicum (L.) DC. in Lam. and DC. Fl. Franc. 3rd 

 ed., 2:365. 1805. 

 Lichen geographicus Linn. Sp. PI. 1140. 1753. 

 Buellia geographica (L.) Tuck. 



Thallus citron yellow (R) or clear dull green yellow (R), determinate, 

 thin to moderately thick, warty, or areolate, areoles flat to slightly convex, 

 smooth, usually contiguous, rarely somewhat scattered on a black hypo- 

 thallus. Apothecia angular, usually crowded, 0.4-1.0 mm. in diameter, 

 partly immersed between the areoles ; disk black, flat ; proper margin con- 

 colorous with the disk, thin, finally disappearing ; hypothecium dark brown ; 

 paraphyses loosely coherent, with brownish black tips; asci 8-spored; 

 spores dark brown, oblong-ellipsoid, muriform, 17.0-40.0 x 11.0-20.0 fx. 



On rocks : Pierce Co. : Mt. Rainier, Berkeley Park, 6000 ft., 1940, 3029. 

 Yakima Co. : Dewey Lake, 4800 ft., 1940, 2790; American River Camp, 

 2800 ft, 1931, 957. Jefferson Co. : Mt. Olympus, on the summit, 8200 ft., 

 1906, Frye 72 (W). Olympic Mountains, Boulder Peak, 5500 ft., A. H. 

 Smith, 2859 (F). Whitman Co.: Pullman, R. K. Beattie 53 (F). 



A very conspicuous alpine rock lichen, easily recognized by the yellow 

 thallus with the black apothecia immersed in it. 



