IOWA ACADEMY OP SCIENCE 
25 
Diseases of 1907 by Orton and Ames, it is reported from eight different states 
from Maine to Montana. The fruit bodies are somewhat hoof-shaped, very 
hard, the upper surface black, while the fruiting surface is cinnamon brown. 
They are 4 — 8 inches long, 2 — 4 inches broad, — 5 inches thick, and alv/ays 
occur singly. The hymenium is made up of rounded pores. The upper surface 
is marked by concentric furrows and ridges which mark off the annual layers. 
Thus the fungus is perennial. 
The location of the sporophore on its host leads us to the question of the 
conditions favoring the entrance of the fungus. Since the mycelium cannot 
enter through the living cambium layer of the tree, some means of infection 
must be provided. These infection areas are provided in a variety of ways. 
From, the location of the sporophore on the poplar at the knot-holes, we con- 
clude th«,t it gains entrance through the dying away of the lower limbs, and 
nature failing to heal the wound formed. The sporophores found upon butter- 
nut, iron-wood, and the apple were each located at a wound. Hence we con- 
clude that the fungus must be a wound parasite. The microscopic spores 
found lodgement in the wounded area, and when proper moisture was obtained 
it germinated, sending its hyphae into the heart wood. After it had received 
the proper nourishment, a sporophore was formed, and spores produced. The 
number of sporophores on a host varies from one to twenty-five. 
Cross sections of a poplar tree present a very characteristic marking of the 
wood due to the different stages of decay and the coloration of the wood. The 
more advanced stages of decay lie at the center, the less advanced at the outer 
edge. It changes the heart wood to a light yellow color, and a very dark line 
separates it from the outer area which is a dark brown color from the knot- 
holes to the center there is the same condition, showing its entrance. Atkin- 
son (3) stated, “that the peculiar discoloration of the wood accompanied the 
mycelium of this specie of fungus, and might be sufficient to identify the 
species even where no fruit forms of the fungus were present.” 
Pyropolyporus igniarius was found in greatest abundance infecting the pop- 
lar (Populus grandidentata), in fact, only one specimen was found on each 
of the apple and iron-wood, while several were found on the butter-nut. The 
fungus appeared to effect the black poplar more than it did the white; and it 
appeared to attack no trees less than five inches in diameter. In some groves 
of poplar the greater per cent of them were infected, while in others it was 
not so prominent. 
The effects are easily to be seen in some localities where a greater number 
of the trees lie on the ground. From this we might conclude that it effects 
the tree as a whole, causing its decay and finally its fall. To estimate the pos- 
sible loss is a difficult task; but as these trees are somewhat limited in quan- 
tity in localities we can readily see that the damage is great. If the tree is 
not used before it falls, the wood is of but little value, and, as far as lumber 
purposes is concerned it is of no value whatever. This fungus is' not so 
serious as a hard wood disease, for it effects only our less important forest 
trees. 
Poropolyporus Everhartii: This fungus is found to infest the broad leaved 
woods of this region, the hardiest and best of our timber, the red and white 
oak. We find this fungus is not as widely distributed over the United States 
as the former, and is only known on the oak and occasionally on the beech. 
In Plant Diseases of 1907 it is not reported. 
