62 
IOWA ACADEMY OF SCIENCES 
For the sake of the record of distribution of such lichen societies, 
it will be worth while to record here the lichens found in the two 
kinds of societies as follows, the plants occurring in the societies on 
Bald Mound, on Johnson’s Mound, on the esker and on the rounded 
hills near by, unless otherwise indicated in the list of species below. 
LECANORA CALCAREA CONTORTA FORMATIONS. 
Y erriicaria nigrcscens. 
Y errucaria muralis. 
Y erriicaria fuscella. 
Flacodium vitelUnum aurellum, and other species. 
Lecanora calcarea contoria. 
BiatoreUa {Lecanora) pruinosa, on Bald Mound only. 
Dermatocarpon (Enclocarpon) pusillum. 
Kincdina Mscho/fii, not found at Bald Mound. 
PSORA DECIPIENS LICHEN FORMATIONS OF EXPOSED CALCAR- 
EOUS EARTH. 
Endocarpon hepaticum. 
Pcora (Eiatora) decipiens. 
Hcppia despreauxii, not found at Bald Mound. 
Bacidia {Biatora) muscorum, Johnson’s Mound and roTind hill only. 
A summary of previous studies of similar lichen tormations else- 
where may be found in Minn. Bet. Stud. 2:GG8-G70, My 1901. CoiTipari- 
son of the above lists of species with the data recorded in the above 
citation shows that the societies studied in Illinois are rather poorer 
in point of species than the similar ones in Iowa and -Minnesota, ihis 
Ls doubtless due in part to the fact that nearly all of the area studied 
in Illinois had been pastured more or less and also no doubt partly to 
the fact that the conditions in Illinois are on the whole less xerophytic 
than those of Iowa and Minnesota. Both of these factor's would ahect 
the earth lichens more than those of the rocks, the seed plants occu- 
pying the soil more completely in the less xerophytic region so that 
the lichen societies of the earth are reduced more than those of the 
recks, v/hile the pasturing acts in the same way. 
The distribution of trees and of Poa compressa at the esker has 
been noticed, and the distribution of trees along both sides of the xero- 
pliytic crov'n of the Johnson’s Mound is well shown in Pig. 3, the 
w'oods bordering the narrov/ xerophytic formations on both sides. The 
full list of xerophytic spermaphytes found on the four hills, and nearly 
all of them on the esker, is as follows: 
Scuiellaria parvula. 
A^rcnari a plantag ini folia. 
Yiola pedata. 
Erigeron strigosus. 
Pctalostemon sp. 
Solidago nemoralis. 
Arenaria michauxii. 
Poa compressa. 
Yer I cn a cmgustifo I ia. 
Yertena stricta. 
Sysyi'inc Ilium sp. 
Andropogon scoparius. 
Echinospermum lappula. 
Litliospermum angustifolium. 
