IOWA ACADEMY OP SCIENCES. 
75 
Parmelia conspersa (Ehrh.) Ach. The most common lichen 
on the exposure, covering large areas of rock. 
Physia ccesia (Hoffm.) Myl. Not common. 
Omphalaria . An undescribed species found in 
Iowa, Minnesota and Nebraska. Not common. 
Pertusaria sp. (?) Not common. 
Endocarpon miniatum (L. ) Schaer. Rare. Probably a variei y. 
The lichen flora of the exposure, very conspicuous by its 
abundance and variety, is an exceedingly interesting one. The 
rock in many places is fairly covered with these persistent 
forms, and the species are, for the most part, identical with 
those which occur on surface granite boulders in the northern 
or northeastern part of the state. 
In addition to the species given in the preceding list, there 
are several which may be found almost anywhere on the 
prairies, and which readily adapt themselves to new surround- 
ings, yet are properly dry ground species. They are: 
Delphinium azureum Mx. Not common. 
Psoralea argophylla Pursh. Not rare. 
Psoralea esculenta Pursh. Rather rare. 
Gastilleia sessiliflora Pursh. Rare. 
Hedeoma pulegioides Pers. Very common. 
Juncus tenuis Willd. Common. 
Gar ex cephalophora Muhl. Not common. 
Garex straminea Willd. , var. hrevior Dewey. Quite common. 
Garex stramineal^iWdi., YBX. Not common. 
Andropogon scoparius Mx.* Common. 
Stipa spartea Trin. Common. 
Muhlenbergia glomerata Trin. Not common. 
Spordbolus cuspidatus Torr. Common. 
Galamagrostis canadensis Beauv. Common. 
Galamagrostis longifolia Hook. Common. 
This report would be incomplete without a list of the species 
which were found along the edges of the pools left by the 
streamlets. They do not properly belong to the flora of the 
rock-exposure, but their presence is of interest, especially as 
some of them were observed nowhere else in Lyon county. 
They are: 
Botala ramosior Koehne. Not common. Known heretofore 
only from Benton and Henry counties. 
*For the identification of some of these grasses thanks are due to Prof. L. H. 
Pammel. 
