MICHIGAN ACADEMY OF SCIENCE. 
47 
MYCORHIZA-PRODUCING BASIDIOMY CETES.* 
L. H. Pennington. 
A review of the recent literature shows that considerable attention has 
been paid to endotrophic mycorhiza. At the same time very little has been 
done with the so-called ectotrophic mycorhiza. This condition is probably 
due to the fact that in the case of endotrophic mycorhiza, the entire fungus 
is within the root and may possibly be isolated and studied by itself, while 
in the ectotrophic relationship the fungus is an unknown and uncertain 
factor. Any observations, therefore, which reveal the identity of fungi 
which enter into mvcorhizal relations with higher plants is of interest and 
importance in the study of mycorhiza problems. 
The fungi which have been found to produce mycorhiza upon the roots 
of trees belong with few exceptions to the Basidiomvcetes. Rees (1) first 
called attention to the connection of Elaphomyces with the ectotrophic 
mycorhiza of forest trees. Noack (2) then followed with some observations 
in which he showed that the mycelia of Geaster fornicatus Fr. and Geaster 
Jimbriatus Fr. are connected with the mycorhiza of pines. This discovery 
led him to further search until he established a mvcorhizal relation in the 
following instances: Tricholoma russula Schaef. with beech roots, Tricho- 
loma terreus Schaef. with pine and beech, Lactarius piperatus Fr. with Fagus 
sylvaticus and Quercus pedunculata, Lactarius Valerius with beech. Corti- 
narius collisteus Fr. with pines, Cortinarius caerulescens Schaef. with beech, 
and Cortinarius fulmineus Fr. with o&k. Woronin (3) merely suggested 
that some Boleti might be connected with the mycorhiza of trees. No 
other observers entered this field until Kauffman (4) showed the connection 
of Cortinarius rubipes Kauff. with three forest symbionts. The observa- 
vations given below may be considered as a continuation of the work begun 
by Dr. Kauffman. 
During the summer of 1907, the writer had occasion to spend considerable 
time collecting fleshy fungi in the vicinity of Ann Arbor. On July 25. while 
collecting with Mr. J. S. Bordner in the woodlots west of Whitmore Lake, 
many specimens of Russula emetica Fr. were found growing in the rotten 
wood of much decayed logs. We noticed that every time we dug up a sporo - 
phore we also exposed mycorhiza structures upon a certain kind of rootlets 
Young sporophores were found within a few millimeters of mycorhiza struc-. 
tures, and the fine mycelium which is found converging at the base of a 
mushroom stem was found surrounding and apparently connected with these 
mycorhiza structures. Further search showed that the same conditions 
held true in every instance where this Russula was found growing in rotten 
logs. In similar situations where the Russula was not found, mycorhiza 
structures were not always found. The mycelium of this Russula was always 
found associated with the mycorhiza of one kind of roots only, which were 
found to be of the Red Oak. The decayed logs in which the Russula grew 
were in some instances identified as Red Oak also. 
A few days later in the same woodlot, I found another form of Russula 
Contribution 96 from the Botanical Laboratory of the University of Michigan. 
