178 LICHENS OF THE STATE OF WASHINGTON 



This species is easily separated from Physcia pulverulenta by the dark 

 under surface and the abundantly sorediate margin. 



5. Physcia muscigena (Ach.) Nyl. Act. Soc. Linn. Bordeaux 21 :308. 



1856. 

 Parmelia muscigena Ach. Lichenogr. Univers. 472. 1810. 

 Physcia pulverulenta var. muscigena (Ach.) Nyl, 



Thallus grayish brown or brown, foliose, spreading irregularly, lobes 

 divided, short and broad, tips widened like a fan, margins crenate, ascend- 

 ing, pruinose over the whole surface or only at the tips, margins sometimes 

 sorediate, medulla yellow, green, or white ; below dark brown or black, paler 

 near the circumference, covered with black rhizoids ; loosely attached to 

 the substratum. Apothecia small and rare, no Washington material seen 

 fruiting by the writer, apothecia 1.0-2.0 mm. in diameter, sessile; disk 

 black, more or less pruinose, concave to flat, thalline margin thick, per- 

 sistent, entire or crenate, becoming sorediate, hypothecium pale brown; 

 spores brown, ellipsoid, 1-septate, 22.0-26.4 x 10.0-14.8 fx. This descrip- 

 tion was made from a specimen in Hasse Herbarium No. 188, collected 

 Ventura Co., Calif. (S). 



On trees, moss, or a thin layer of soil over rock : Yakima Co. : near 

 Naches Ranger Station, 2400 ft., 1940, 3327; gulch near Naches, 1350 ft., 

 1931, 905. Ferry Co.: near Republic, 2400 ft., 1940, 3140. Olympic Moun- 

 tains, 6000 ft., 1915, /. M. Grant (F). Ferry Co.: Republic, 1912, Foster 

 2360 (F). San Juan Co.: Waldron Island, 1906, Fink 255 (W), this 

 specimen determined as Physcia pulverulenta by Fink. 



The dark color of the thallus separates this species from any other, 

 species of Physcia. 



6. Physcia pulverulenta (Schreb.) Hampe in Fiirnr. Nat. Topogr. Re- 



gensburg, 2 :249. 1839. 

 Lichen pulverulentus Schreb. Spicil. Fl. Lipsiens. 128. 1771. 



Thallus pearl gray (R), pale drab-gray (R), or almost white, foliose, 

 circular, closely appressed, usually white pruinose, lobes much divided, 

 flat, smooth, often elongated, narrow, imbricated, tips wider, rounder, trun- 

 cate or emarginate, margins entire, crenate or rarely lobulate, sometimes 

 ascending, the central part of the thallus is often sparingly to abundantly 

 covered with narrow secondary branches, medulla white; below brownish 

 black or black, paler toward the margins, bearing numerous brown or 

 black rhizoids. Apothecia rare, 1.0-4.5 mm. in diameter, sessile; disk dark 

 brown or dark gray, white pruinose, concave or flat ; thalline margin thick, 

 persistent, crenate or lobulate; hypothecium pale brown; spores brown, 

 oblong-ellipsoid, 1-septate, 23.0-34.5 x 14.0-21.0 fi. 



On trees, old wood, rocks, moss, and soil : Chelan Co. : Beaver Summit, 

 2800 ft., 1931, 1334; Entiat, 800 ft., 1931, 1108. Yakima Co. : Naches 

 Ranger Station, 2100 ft., 1940, 3323. Klickitat Co. : Goldendale, 2000 ft.. 



