182 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 
13. Lecanora erysibe (Ach.) Nyl. Not. Sallsk. Faun. Flor. Fenn. 5: 167. 1861. 
Lichen erysibe Ach. Lich. Suec. 50. 1798. 
Thallus crustose and somewhat thin, composed of olivaceous granules, which vary 
in color toward ashy or greenish, and run together to form a leprose or subareolate 
crust, suborbicular and 10 to 25 mm. in diameter, or more frequently irregular and 
more widely spread over the substratum, the areoles or granules rarely somewhat 
scattered; apothecia small or minute, 0.5 to 1 mm. in diameter, adnate, the disk flat 
or more or less convex, brown (in ours more usually black or blackish-brown), the 
exciple entire or crenulate, sometimes disappearing; hypothecium pale; hymenium 
pale beneath and brownish above; paraphyses simple or rarely branched, often 
slightly enlarged and darker toward the apex; asci clavate to cylindrico-clavate; 
spores ellipsoid, sometimes obscurely 2-celled, 10 to 14 » long and 4 to 6 » wide. 
Collected at Minneapolis, at Mankato, and at Granite Falls. On rocks. 
Elsewhere in North America in Illinois and Iowa. Known also in Europe. 
14. Lecanora pallescens (L.) Schaer. Enum. Lich. Eur. 78. 1850. 
Lichen pallescens L. Sp. Pl. 1142. 1753. 
Thallus crustose, of moderate thickness and smoothish and chinky or becoming 
plicate, rarely rugose or even tuberculate-areolate, whitish or darker-ashy, subor- 
bicular and of medium size, 15 to 60 mm. in diameter, or irregular and more widely 
spread over the substratum; apothecia middle-sized or larger, 1 to 2.5 mm. in diam- 
eter, the disk flat or more or less concave, flesh-colored varying toward whitish or 
yellowish, usually more or less white-pruinose, the exciple erect and entire or sub- 
entire; hypothecium pale; hymenium of the same color; paraphyses simple or rarely 
branched, frequently somewhat enlarged and colored toward the apex; asci clavate, 
cylindrico-clavate, or variously irregular, the whole wall thickened; spores ellipsoid 
and ovoid-ellipsoid, said to be 50 to 90 » long and 20 to 40 » wide, but ours some- 
times only 35 » long. 
The above and the next following are scarcely well differentiated in our lichen 
flora and the determinations are difficult and uncertain. 
Found throughout the northern portion of the State. On trees and most common 
on cedars in swamps. 
Distributed throughout North America. Known in all of the grand divisions 
except Australia. 
15. Lecanora tartarea (L.) Ach. Lich. Univ. 371. pl. 7. /. 3. 1810. 
Lichen tartareus L. Sp. Pl. 1141. 1753. 
Thallus crustose, thicker, and more roughened than in the last (tartareous), com- 
posed of coarser granules, which may be conglomerate and form a thick crust or more 
scattered when the crust is very uneven, of the same color as the last, and similarly 
disposed upon the substratum; apothecia middle-sized or large, 1 to 3 or in material 
from other States even 5 mm, in diameter, sessile or adnate, the disk yellowish and 
passing into brownish or brick-colored, scarcely pruinose, flat or concave, the exciple 
rather thick and entire or wavy; hypothecium pale; hymenium pale below and fre- 
quently more or less brownish above; paraphyses very slender, simple or rarely 
branched, sometimes slightly enlarged and colored toward the apex; asci clavate or 
more or less irregular, the walls thickened; spores ellipsoid to ovoid-ellipsoid, 30 to 
65 » long and 20 to 35 » wide. 
Collected at Ely, Some material referred to the last from the trees seems quite as 
much like the present, following Tuckerman’s idea as to spore measurements. The 
collection from Ely, which undoubtedly belongs here, was made on rocks. 
Generally distributed over North America, but hardly so common as the last, 
Known also in all of the grand divisions except Australia, 
