276 35. GYROPHORACEAE [ 135. Umbilicaria 



brown or black rhizoids; apothecia small to middle-sized, 0.4-2.5 mm. across, in- 

 frequent, closely adnate, rare, usually near the margin, the disk convex, black, 

 becoming closely folded, the blackish exciple disappearing; hypothecium dark 

 brown; spores short-ellipsoid, 8-14X5.3-8/*. 



On rocks, usually at high elevation, throughout the United States. 



18. Gyrophora Dillenii (Tuck.) Mull. Arg., Flora 72:364. 1889. 



Umbilicaria Dillenii Tuck., Proc. Am. Acad. 1:264. 1848. 



Thallus large to very large, smooth, brown to dark or ashy brown, the margin 

 torn and irregular; black below with strong black rhizoids; apothecia middle-sized 

 to large, 1-4 mm. across, infrequent, subsessile, round, the disk convex and black, 

 becoming closely folded, the dark exciple disappearing; hypothecium light to darker 

 brown; spores ellipsoid, 17-24X9-14/*. (Plate 26.) 



On rocks, from Maine to South Carolina, and westward to Oklahoma and 

 Minnesota (at high elevation southward). 



OTHER SPECIES REPORTED 

 Gyrophora hirsuta Ach. — California. 



135. Umbilicaria Hoffm., Descr. PI. Crypt. 1:7. pi. 2, f. 1-4. 1790. 



Thallus foliose, irregular or lobed, smooth to very rough, attached to the sub- 

 stratum by an umbilicus, differentiated into well-developed, plectenchymatous, 

 upper and lower cortices, the upper much thinner, distinct algal and medullary 

 layers; apothecia small to middle-sized, closely adnate to substipitate, the disk 

 flat to more or less convex, becoming folded and irregular, the exciple colored like 

 the disk; hypothecium brownish to brown; hymenium brownish: paraphyses 

 branched; asci clavate; spores 1-8, brown or rarely hyaline, ellipsoid to oblong- 

 ellipsoid, transversely and longitudinally septate. 



The algal host is Pleurococcus. 



A. Thallus very black below, covered here and there with 



strong black rhizoids 2. U. caroliniana 



A. Thallus grayish to brownish black below, rarely 

 with few scattered rhizoids 



B. Thallus more or less coarsely papillose above; 

 pitted below 



C. Brownish black below 3. U. pennsylvanica 



C. Grayish to rarely dark brown below 4. U. pustulata 



B. Thallus smooth above; not pitted below 1. U. semitensis 



1. Umbilicaria semitensis Tuck., Gen. Lich. 31. 1872. 



U. angulata var. semitensis Tuck. 



Thallus small to middle-sized, smooth to finely areolate or granulose, ashy gray, 

 varying toward brown, becoming several-lobed with undulate margins; grayish 

 black to black below, granulose to lacerate and ridged, with scattered rhizoids rising 

 from the ridges; apothecia small to middle-sized, 0.5-3 mm. across, closely adnate, 

 round to irregular, the disk flat to convex, becoming closely folded, the exciple 

 well developed, becoming flexuous; hypothecium brown; spores usually 1-2, oblong- 

 ellipsoid, hyaline to finally brown, 5-7-septate transversely and 1-3-septate longi- 

 tudinally, 20-30 X 13-21 /*. 



On rocks, southern California. 



2. Umbilicaria caroliniana Tuck., Proc. Am. Acad. 12:167. 1877. 



U . mammilla ta Tuck, (non Ach.) 



Thallus ,small to middle-sized, olive to blackish brown, becoming deeply lobed, 

 thin, very smooth, irregularly or inconspicuously papillose; very black, pitted and 

 granulose below, and covered here and there with strong black rhizoids; apothecia 

 small to middle-sized, 0.4-1 mm. across, round to elongated, substipitate, the disk 

 flat, black, soon folded and finally proliferous; spores 1 or rarely 2, ellipsoid, brown, 

 11-19-septate transversely and 3-7-septate longitudinally, 30-42 X 20-24 /x. 



On rocks, mountains of North Carolina. 



