46 
TENTH REPORT. 
MYCORHIZAE ON MICHIGAN TREES. 
(abstract.) 
The study of mycorhizae was taken up by the writers in the fall of 1907. 
During the fall, before the ground became frozen, specimens of the roots of 
nearly all the forest trees in the vicinity of Ann Arbor were obtained and 
note taken of the occurrence of mycorhizae as nearly as could be ascertained 
by superficial examination. Later in the year sections of acid fixed portions 
of the roots were cut and stained with anilin, safranin, methyl blue and by 
Gram’s method. These sections were studied under the microscope and the 
presence and character of the mycorhiza determined. 
Out of the 26 species of forest tree roots which were collected and micro- 
scopically examined, 16 were found to be ectotropically mycorhizal, 7 to 
be endotropically mycorhizal and three to be apparently free from any 
fungal affection. The ectotrophic species were the red, white and black 
oak, the tamarack, the Norway pine, the chestnut, the American elm, the 
mockernut and bitternut hickories, the beech, the blue beech, the ironwood, 
the black cherry, the trembling aspen, the poplar (Populus grandidentata) 
and the paper bark birch (Betula papyrifera.) 
The enclotrophic species were the swamp and sugar maple, the bass wood, 
the horse chestnut, the walnut, the butternut and the sycamore. Those 
that showed no mycorhiza as far as we were able to determine were the ashes, 
black and white, and the willow, while a merely superficial examination of 
the tulip tree, Ailanthus glandulosa and the papaw would seem to indicate 
that they too were unaffected. 
G. A. Duthie, 
D. M. Matthews. 
