FINK—THE LICHENS OF MINNESOTA. 165 
KEY TO THE SPECIES. 
Thallus more or less tomentose above..........-..---+-++----- 1. NN. tomentosa. 
Thallus not tomentose above. 
Tomentose beneath..........----------- ee ee cere ete 2. N. helvetica. 
Without rhizoids beneath. 
Without soredia above..........-.-------+-+20++2---- 3. N. laevigata. 
Bearing soredia above........-------+-+-+-++0 -+++--- 3a. N. laevigata par- 
alts. 
1. Nephroma tomentosa (Hoffm.) Koerb. Syst. Lich. 56. 1855. 
Peltigera tomentosa Hoffm. Deutsch. Fl. 2: 108. 1795. 
Thallus somewhat closely attached to the substratum by means of the larger rhi- 
zoids, more or less orbicular in outline, middle-sized or larger, 5 to 12.5 or even rarely 
20 cm. in diameter, the upper surface more or less tomentose at least along the 
margins; from sea-green varying to lead-colored or brown, the lobes not much elon- 
gated, except the fertile ones, sinuately cut with the ends subentire or crenate, 
beneath light-colored, tomentose with small rhizoids usually interspersed with larger 
ones, quite commonly more or less beset with small whitish tubercles (pseudocy- 
phella); apothecia frequent, the disk reddish brown, the thalloid margin frequently 
persistent and entire or irregularly crenulate; middle-sized to large, 2 to 12 mm. in 
diameter; hypothecium brownish or pale; hymenium pale, or pale brownish above; 
paraphyses commonly simple, the apex usually somewhat thickened and brownish; 
asci clavate; spores light brown, fusiform to oblong, 4 to 6-celled, 19 to 25 » long and 
4 to 6 » wide. 
Confined to the northern portion of the State. On rocks and trees. 
Found from the Atlantic to the Pacific in the extreme northern portion of the 
United States and northward throughout British America and Alaska. Known in 
all the grand divisions except South America and Australia. 
2. Nephroma helvetica Ach. Lich. Univ. 523. 1810. 
Thallus quite similar to that of the last, but smaller (40 to 90 mm. in diameter) 
and more irregular in form, not tomentose above, but the margins and frequently 
the upper surface bearing tooth-like branchlets, sea-green or more commonly more 
or less brown, more deeply, narrowly, and sinuately or laciniately lobed than the 
last. with the ends of the lobes scarcely ever even subentire, but either laciniate or 
somewhat irregularly crenate; beneath finely and less constantly tomentose than in 
the last, the color commonly darker or even blackish, the tubercles wanting; apo- 
thecia frequent, the disk reddish brown or darker, the margin as in the last, middle- 
sized, 1.5 to 6 mm. in diameter; hypothecium pale or brownish; hymenium pale 
beneath and pale or brownish above; paraphyses commonly simple, the apex usu- 
ally thickened and brownish; asci clavate, the apical wall somewhat thickened; 
spores brown, ellipsoid to subfusiform, 4-celled, 15 to 22 » long and 5 to 8.5 » wide. 
Confined to the northern portion of the State, but once collected as far south as 
Taylors Falls. On rocks or trees or rarely on earth. 
Widely distributed in North America. Known in all the grand divisions. 
3. Nephroma laevigata Ach. Syn. Meth. Lich. 242. 1814. 
Thallus irregular or somewhat orbicular-rosulate, smooth or somewhat wrinkled 
above, sea-green or more commonly brown in color, the lobes rounded and undulate, 
beneath usually pale and wrinkled and quite devoid of rhizoids, though often rough- 
ened with what appear under the microscope as very short rhizoids; apothecia rather 
rare in ours, the disk reddish brown, small to middle-sized, 2 to 5.5 mm. in diameter, 
the thalloid margin entire in the material at hand; hypothecium brownish; hyme- 
nium pale below and pale or brownish above; paraphyses simple or rarely branched, 
the apices usually thickened and brownish; asci clavate; spores fusiform-ellipsoid, 
light brown, 4-celled, 16 to 22 4 long and 4 to 6.5 » wide. 
