Nov. io, 1913 
Heart-Rots of Hardwood Trees 
113 
leaving a permanent opening into the heartwood of the trunk just below 
the surface of the ground. Through such hidden openings the mycelium 
of any heart-rotting fungus capable of growing in the forest debris could 
enter the tree, and thus the resultant rot would be directly associated with 
the old fire scar; (3) some of these heart-rotting fungi may be able to 
enter through sound, unbroken living roots and then move upward as a 
heart-rot into the bole of the tree. In this case they would also be true 
root parasites and not simply mere heart-rotting fungi. 
None of the three rots discussed in this article are known to be true 
root parasites. As to the first objection mentioned, the writer has inves¬ 
tigated several hundred uprooted oak stumps, many of which had heart- 
rot, and in no instance was any evidence found indicating that the heart- 
rotting fungus entered through the roots and thence worked upward in 
the tree. On the contrary, repeated instances were found where the rot 
began at the surface of the ground in an old fire scar or other wound and 
moved downward in the heartwood of the root and upward in the bole of 
the tree. In every case where the rot had entered the roots it had 
evidently come from above and not from below, as the rot was limited to 
the heartwood of the root, while the sapwood was alive and sound. 
However, there is a large wood borer which lives in the roots of oaks, 
and when its burrows reach the surface of the roots an opening would be 
made for any fungi to enter from the soil. It is well known that in the 
roots of oaks the amount of heartwood compared to that of sapwood is 
very small. This in itself makes improbable the entrance of heart-rotting 
fungi through the roots, especially sound ones. 
In regard to the second objection mentioned, the writer has recently 
examined more than 200 oak trees with fire-scarred bases, and not a single 
one was found in which the wounds having healed above ground had 
not also completely healed over below the ground. As a rule, forest fires 
injure the tree but a short distance, 2 to 3 inches, below the collar of the 
tree, owing to the protection of the soil. Therefore, it is not impossible 
for these three heart-rotting fungi to enter through the root system; but 
taking the above facts into consideration it is improbable that they did 
enter by this route, even granting that they are capable of leading a 
purely saprophytic existence in the soil and forest debris—a condition 
yet to be proved. 
The very close association of the heart-rots with the old fire scars in 
the trees studied is so evident that undoubtedly the causal fungi entered 
the tree by this route. So marked is this association of fire scars with 
heart-rots in the Ozarks that one could tell the areas in the forest which 
had been most frequently burned over from the percentage of trees 
affected with heart-rots. 
The writer has found three types of heart-rotting fungi in living trees: 
(1) Those limited to the base and lower portion or butt of the tree, for 
example, Polyporus berkeleyi and P. frondosus; (2) those which are able 
