194 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 
Sterile and on the whole appearing more like Parmelia perlata except for the pale 
color. 
Once collected, at Grand Portage on rocks. 
A strictly North American plant, reported from widely separate areas in the 
United States and Mexico. 
8. Parmelia cetrata Ach. Syn. Meth. Lich. 198. 1814. 
Thallus usually large, 8.5 to 16.5 cm. in diameter, prostrate, the- lobes frequently 
crowded and much more ascendant than in the last, the margins of the lobes some- 
times densely sorediate and, in ours at least, sometimes quite ciliate, rather thinner 
than the last and less inclined to become rugose toward the center, the upper surface 
light or darker sea-green, beneath black but usually brown toward the margin, clothed 
with rhizoids rather smaller than those of the last. 
Ours sterile—fruited specimens not seen; apothecia and spores said to be like those 
of the last, of which Nylander regarded it as a subspecies. 
A rare lichen in Minnesota. Two specimens were collected on rocks at Granite 
Falls. No. 513 from that place is undoubtedly this species, having the more as- 
cendant, densely crowded, and strongly sorediate lobes. No. 514 is an intermediate 
form, quite as near the last species above. 
Tuckerman gives the species a wide North American distribution, and it seems to 
be a strictly American lichen. Known in South America also. 
4. Parmelia crinita Ach. Syn. Meth. Lich. 196. 1814. 
Thallus usually large, 7.5 to 16 cm. in diameter, prostrate with slightly ascendant 
margin, densely beset with granules or isidioid branchlets, light or darker sea-green, 
the lobes rather large, rounded and frequently imbricate, their margins rather incon- 
spicuously ciliate and entire, somewhat irregular or crenate, beneath black or rarely 
partly brown, usually of the latter color toward the margins, the lower surface clothed 
with rhizoids like those of the last species; apothecia subpedicellate, rare, those 
examined small (3 to 5 mm.), though Nylander gives 4 to 14 mm. in diameter, deeply 
concave, the disk chestnut, the margin crenate, irregular or isidioid, frequently 
ciliate; hypothecium pale or yellowish; hymenium pale below and brownish above; 
paraphyses simple, slender, the tips pale or yellowish and usually thickened; asci 
broadly clavate; spores simple, ellipsoid, their walls thick, 17 to 22 « long and 9 to 
15 » wide. 
Generally distributed over the State, but by no means common. On trees and 
rarely on rocks. 
Distributed throughout the United States and Canada. Also known in South 
America, Europe, and Africa. 
5. Parmelia tiliacea (Hoffm.) Ach. Meth. Lich. 215, 1803. PLATE 36, A. 
Lichen tiliaceus Hoffm. Enum. Lich. Icon. 26. pl. 16. f. 2. 1784. 
Thallus closely adnate, suborbicular in outline, rather small, 30 to 90 mm. in 
diameter, sea-green, the upper surface commonly rugose, especially toward the center, 
the lobes rather short and rounded, with crenate or irregularly divided margins or 
rarely elongated and subdichotomously divided, beneath black and densely covered 
with black rhizoids; apothecia sessile or subpedicellate, frequent and of medium 
size, 3 to 12 mm, in diameter, deeply concave or rarely nearly flat, the disk chestnut, 
the margin crenulate to crenate or rarely entire; hypothecium pale; hymenium pale 
or very slightly colored; paraphyses simple or rarely branched, slender, the apex 
pale or brownish and thickened; asci clavate; spores short-ellipsoid, 5 to 11 » long 
and 5 to 7 # wide. : 
Generally distributed over the State, but rare in the northeastern portion. On 
trees, old wood, and rocks. 
