190 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 
Found in several localities in the northern portion of the State. On hard wood trees, 
especially oaks and cottonwood, and to be looked for wherever these trees occur in 
northern Minnesota. Besides the localities noted in the sixth preliminary report, the 
plant was seen in 1902 at several points on the north shore of Lake Superior from Grand 
Marais to Duluth. 
A North American lichen not known elsewhere. 
6. Pertusaria leioplaca (Ach.) Schaer. Lich. Helv. Spic. 2: 66. 1823. 
Porina leioplaca Ach. Lich. Univ. 309. pl. 7. f. 2. 1810. 
Thallus thin and smooth or becoming somewhat chinky and verrucose, sea-green to 
pale yellowish, disposed upon the substratum much as in the last, but the patches on 
the whole smaller, also inclined to hypophloodal conditions, some of ours showing a 
poorly developed upper cellular cortex (this no doubt sometimes existing in specimens 
of other species not thus credited, the plants varying somewhat in this respect even 
within a species); apothecia-containing verrucz small to middle-sized 0.6 to 2 mm. in 
diameter, hemispherical and somewhat irregular, scattered or crowded; apothecia one 
or few in each verruca, the pore rarely depressed and sometimes becoming black and 
conspicuous, or the whole verruca rarely becoming depressed and disk-like; hypothe- 
cium pale; hymenium pale beneath and commonly brownish above; paraphyses com- 
monly branched and rarely somewhat enlarged toward the apex; asci cylindrico- 
clavate; spores oblong-ellipsoid, 4 to 8 in each ascus and varying in size according to 
number, hence 40 to 180 » long and 20 to 50 » wide. 
Not often collected, but no doubt generally distributed over the State. On trees. 
Found throughout North America. Known in all of the grand divisions. 
FAMILY PARMELIACEAE. 
This family is represented in our flora by 6 genera, of which Parmelia is the largest, 
having more than 20 forms in the State. However, the whole family with its 6 genera 
has not as many species in our flora as the Cladoniaceae with their single genus. The 
family is most closely related to the Lecanoraceae below and to the Physciaceae and the 
Teloschistaceae above. The relationship with the Lecanoraceae was stated in the dis- 
cussion of that family. Of the two families next preceding this it is not so easy to 
decide which is more closely related to it. If we consider superficial resemblance in 
color and form of thallus, doubtless the genus Physcia of the Physciaceae would stand 
nearest, but the spore characters should doubtless have greater weight. As regards the 
latter, the 2-celled spores of Ramalina look somewhat toward the similar but brown 
spores of Physcia, while colored spores are also found in the present family in Alectoria, 
Turning to the Teloschistaceae, however, every condition from the typical polar 
2-celled spore to the simple spore is found in both of the two genera of the family, the 
nonpolar 2-celled spores being quite like those of Ramalina, and the much rarer simple 
ones not very different from those of the Parmelias. Thus we may bridge over an 
apparent difficulty in the polar spores, so that the Teloschistaceae appear after all closer 
to the Parmeliaceae than do the Physciaceae, and no doubt the Physciaceae should 
stand highest among the Discocarpineae. 
The thallus is either foliose with dorsiventral symmetry or fruticose with more or 
less well defined radial symmetry, A cellular cortex or a pseudocortex of hyphe is 
always present, the former in the foliose species and the latter usually in the more or 
less plainly fruticose ones. The algal symbiont is Cystococcus. 
The apothecia vary in position from subpedicellate to immersed. The spores are 
simple or 2-celled and almost always colorless, those of some Alectorias being some- 
times brownish. 
PARMELIA Ach. Meth. Lich. xxxm1, 154. pl. 4. f. 8-6. 1803. 
PLATE 35. 
The thallus is foliose or rarely somewhat fruticose, the former in all of ours. In some 
species it is freely dichotomously lobed, while in others it is nearly entire, the margin 
