FINK—THE LICHENS OF MINNESOTA. 37 
DESCRIPTIVE CATALOGUE. 
OUTLINE OF CLASSIFICATION. 
CLASS LICHENES. 
OrDER ASCOLICHENES. 
Lichens in which the spores are produced in asci. All of the Minnesota lichens 
belong here, except perhaps the last family below, in which the fungal symbiont 
may not be an ascomycete. The order Basidiolichenes includes but a few species 
and is confined to tropical regions. 
SUBORDER CONIOCARPINEAE., 
The thallus is crustose, and the alga is Cystococcus, except perhaps in Coniocybe. 
The fungal symbionts belong to the Protocaliciaceae. An erect and rarely branched 
structure, the stipe, arises from the substratum and bears the exciple and the hyme- 
nium. The stipes are devoid of algal cells and are to be regarded as parts of the 
apothecia rather than portions of the thallus. A proper exciple is present. The 
plants are minute and are difficult to detect; the stipes when best developed are only 
0.2 to 2.5 mm. long. 
FAMILY CALICIACEAE (p. 44.) 
Coniocybe. Chaenotheca. 
Calicium. Acolium. 
SUBORDER GRAPHIDINEAE. 
The thallus is crustose in all of ours, and the algal symbiont is Chroolepus, except 
in some Arthonias, where Cystococcus may occur instead. The fungal symbionts 
belong to the suborders Stictidiaceae, Hysterineae, and Patellariaceae. The apo- 
thecia are elongated and often branched, variously irregular, or rarely rounded. The 
fruticose Roccelliaceae, not represented in our flora, probably place the suborder as 
a whole above Ceniocarpineae. 
FAMILY GRAPHIDACEAE (p. 52. 
Opegrapha. Arthonia. 
Graphis. Arthothelium. 
SuBORDER DISCOCARPINEAE. 
The apothecia are commonly disk or cup-shaped, though a few forms show fruits 
nearly closed. The exciple is proper or thalloid or sometimes double when the 
thalloid exciple surrounds the proper exciple. The thallus varies greatly, showing 
crustose, foliose, and fruticose forms as well as various intermediate conditions. 
Likewise, all the forms of algal symbionts at all common in lichen thalli may be looked 
for in the subordet. The fungal symbionts are not easily traceable in most instances 
to their ancestral forms, but they belong, at least mainly, to the Patellariaceae. 
Nearly all of our conspicious lichens belong to the present suborder. 
FamILy LECANACTIDACEAE (p. 59.) 
Melaspilea. Lecanactis. 
lamMILY GYALECTACEAE (p, 61.) 
Gyalecta. Secoliga. 
Conotrema. 
