208 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 
The genus seems closely related to Evernia and yet closer to Alectoria. Nine 
species and subspecies have been reported from Minnesota, of which Usnea barbata is 
the only one generally distributed over the State. 
On trees, old wood, and rarely on rocks, 
The Usneas are difficult to determine in some instances, and some of our species 
and subspecies are by no means certain. 
Type species Lichen plicatus 1. Sp. Pl. 1154.1753. (Usnea barbata plicata(L.) Fr.) 
Based on Coralloides Dill. Muse. pl. 11. f.1, 1741, identified in L. Sp. Pl. 1154, 1753. 
KEY TO THE SPECIES. 
Thallus short, scarcely pendent. 
Thallus sea-green or grayish, 
Thallus usually erect, strigose-fibrillose............... 1. U. barbata. 
Thallus longer and inclined to pendent conditions, 
fibrillose and sorediate............................ la. U. barbata hirta. 
Thallus rusty red, otherwise similar to the last above.____. lb. U. barbata rubi- 
ginea. 
Thallus long and pendent. 
Thallus stout and rigid. 
Trunks angulate. .....2.22.22202.000.0000...00 0. 2. U. angulata. 
Trunks not angulate, quite fibrillose............._... le. U. barbata cerat- 
ina, 
7, cavernosa, 
Ss 
o> 
© 
= 
= 
c 
mm 
—> 
° 
< 
fer) 
° 
— 
7) 
cf 
tes) 
i 
i) 
oO 
i] 
S 
=) 
km 
Oo 
oo 
o 
| 
rs) 
= 
—_ 
+ 
og 
cae) 
5 
igs} 
fas) 
fs 
~ 
Thallus not foveolate-lacunose. 
Branches clothed with fibrils. 
Fibrils long and numerous; the thallus very 
long.... 2.2222. 3. U. longissima, 
Fibrils shorter and less numerous........__.. ld. U. barbata dasy- 
poga. 
Fibrils few or absent............................ le. U. barbata pli- 
cata, 
1. Usnea barbata Fr. Sched. Crit. Lich. Exsice. Suec. 8: 34. 1826. 
Thallus fruticose, stout, erect or spreading, rather short, 20 to 60 mm. in length, 
rigid, branched divaricately, grayish to sea-green in color, more or less strigose, 
fibrillose, the branches and main trunks cylindrical; apothecia terminal or sub- 
terminal, varying considerably as to size, 3 to 10 mm. in diameter, commonly more 
or less concave, the disk pale flesh-colored or slightly brownish or reddish, the margin 
clothed more or less with fibrils, these also frequent on the under side; hypothe- 
cium pale; hymenium pale throughout; paraphyses simple or rarely branched, with 
pale and somewhat thickened tips; asci clavate or cylindrico-clavate; spores ellip- 
soid, 7 to 10 » long and 5 to 6 » wide. 
Generally distributed in the State. On trees and old wood, and rarely on rocks. 
Commonly fruited in the southern part of the State, but not known to fruit northward 
in the State, though quite common. 
This species occurs in all parts of North America and is quite cosmopolitan also 
in its foreign distribution. It is the Usnea barbata florida (L.) Fr.¢ of most authors. 
la. Usnea barbata hirta (L.) Fr. Lich. Eur. 18. 1831. 
Lichen hirtus L. Sp. Pl. 1155. 1753. 
Thallus somewhat more slender and less rigid than the last, consequently less 
often erect but more inclined to be pendent, though not long; more or less fibrillose, 
with small fibrils and thickly sprinkled with soredia, of same color as the last. 
@ Lich, Eur. 18. 1831. 
