129. Rhizocarpon] 33. LECIDEACEAE 237 



D. Thallus squamulose, chestnut-brown to black . . . . 8. R. Bolanderi 

 B. Thallus dirty white to light or darker yellow 

 C. Spores rarely more than 35 /jl in length 



D. Spores 3-septate transversely 18. R. viridiatrum 



D. Spores 3-5- or 7-septate transversely 

 E. Thallus greenish to bright yellow 



F. Thallus chinky to scattered areolate; apothecia 



immersed to adnate 20. R. geographicum 



F. Thallus areolate ; apothecia immersed ... 19. R. lecanorinum 



E. Thallus dirty white to yellowish 17. R. athalloides 



C. Spores 30-78 X 16-24 m 21. R. oidaleum 



1. Rhizocarpon alpicolum (Wahl.) Rabh., Flecht. Eur. fasc. 22. no. 618. 1861. 

 Lecidea atrovirens var. alpicola Wahl., Fl. Lapp. 474. 1812. Lecidea geographica 



var. alpicola (Wahl.) Schaer. Lecidea alpicola (Wahl.) Hepp. Buellia alpi- 

 cola (Wahl.) Anzi. 

 Thallus moderately thick, bright yellow to yellowish gray, chinky to areolate, 

 the areoles rough, flat to slightly convex, continuous or scattered upon a black 

 hypothallus; apothecia small to middle-sized, 0.6-1.8 mm. across, partly immersed 

 to adnate, often clustered, the disk flat to slightly convex, black, the exciple thin, 

 black, finally disappearing; hypothecium dark brown; asci clavate; spores 8, hyaline 

 to dark brown, ellipsoid, 1-septate, 15-28 X 9-14 /x. 

 On rocks, Maine and New Hampshire. 



2. Rhizocarpon Oederi (Web.) Koerb., Par. Lich. 232. 1861. 



Lichen Oederi Web., Spic. Flor. Goett. 182. 1778. Buellia Oederi (Web.) Rostr. 



Thallus thin, yellowish or reddish brown, chinky to areolate or finally warty; 

 apothecia minute, 0.15-O.Smm. across, partly immersed to adnate, the disk flat 

 to slightly convex, dull black, sometimes wrinkled, the exciple thin, black, flex- 

 uous; hypothecium dark brown; asci clavate to inflated-clavate ; spores 8, hyaline 

 to rarely brownish, oblong-ellipsoid, 3-septate, slightly constricted at the septa, 

 16-26 X 7-12 fx. 



On rocks, at high elevations, Maine, New Hampshire, Oregon, and California. 



3. Rhizocarpon vernicomoideum Fink, Ohio Biol. Surv. 2:350. 1921. 



Thallus thin, straw-colored, minutely granulose, the granules convex, scattered 

 or clustered, covering small areas and usually resting upon and bordered wholly 

 or in part by a black hypothallus; apothecia minute to small, 0.2-0.6 mm. across, 

 partly immersed to adnate, the disk flat to convex, black, the exciple thin, promi- 

 nent, black, finally disappearing; hypothecium dark brown; paraphyses branched, 

 semi-distinct; asci clavate; spores 8, brown, oblong-ellipsoid, 3-septate, slightly 

 constricted at the septa, 14-18 X 5-7 [x. 



On rocks, Ohio. 



4. Rhizocarpon postumum (Nyl.) Arm, Flora 53:478. 1870. 

 Lecidea postuma Nyl., Flora 51:345. 1868. 



Thallus thin, ashy to grayish brown, becoming minutely granulose or warty, 

 sometimes disappearing; apothecia minute to small, 0.2-0.6 mm. across, adnate, 

 the disk flat to convex, black, the exciple thin, black, finally disappearing; hypo- 

 thecium brown to brownish, black; paraphyses semi-distinct; asci clavate; spores 

 8, hyaline to brown, ellipsoid to fusiform-ellipsoid, 3-septate transversely and be- 

 coming 1-septate longitudinally, 12-18 X 5-8.5 ju. 



On rocks, Alabama. 



5. Rhizocarpon cinereovirens (Mull. Arg.) Vainio, Act. Soc. Faun. Flor. Fenn. 



53:336. 1922. 

 Patellaria cinereovirens Mull. Arg., Flora 51:49. 1868. R.ignobile T. Fries. 



Buellia concreta (Koerb.) Eckf. 

 Thallus thin, smooth to rough, ashy to grayish brown, becoming minutely 

 granulose, bordered and intersected by the black hypothallus; apothecia minute 



