Nov. io, 1913 
Heart-Rots of Hardwood Trees 
US 
Under the microscope the large, thick-walled, colorless hyphae are plainly 
seen in these holes, and to them the holes undoubtedly owe their origin. 
The edges of the perforated vessels as well as the adjacent cells have been 
delignified. This type of cavity was especially abundant in the wood 
immediately adjacent to the sporophore. 
The final stage of this rot in white oak seems to present one of two 
conditions: If an abundance of air and water is present, all the wood 
fibers will be changed to cellulose, then dissolved, leaving a very light, 
brittle, rotted wood of a dark-brown color, which later gradually crumbles 
into a dirtlike mass. This is the type of rot usually found in dead trees 
or living trees with hollow, open butts. If, on the other hand, only a 
limited amount of air and no rain water is present, as is the case in living 
trees with no open wounds reaching to the diseased heartwood, the rotting 
wood may become honeycombed with empty, cellulose-lined, elliptical 
cavities (PI. VII, fig. 3) or it may decompose into a fibrous mass consist¬ 
ing of long, white cellulose strands and partially decomposed vessels and 
medullary rays. Large quantities of these white cellulose strands are 
often found in the butts of freshly cut trees which externally appear 
perfectly sound but have this rot in the heartwood. 
A Pocketed or Piped Rot in Scarlet Oak 
The following description of the pocketed or piped rot was made from a 
wind-thrown scarlet oak (Quercus coccinea ), which on falling split on the 
upper side for 7 or 8 feet. From this fissure a sporophore of Polyporus 
pilotae protruded. The rot began in the top of the tree and had reached 
the ground. The tree was sawed into 6-foot lengths and split open on 
March 5, and on May 30 fresh sporophores were beginning to form on the 
ends of the split pieces. 
In this host the fungus first attacks the spring wood immediately 
around the larger vessels, turning it to a light-tan color. This change in 
color is accompanied by the absorption, more or less irregularly, of the 
cells of the spring wood, while the wood fibers intermixed with these 
cells are delignified from within outward. The tan color of the affected 
areas is due to the walls of the wood fiber and other cells adjacent to the 
vessels turning a golden yellow. At this stage of the rot the spring 
wood is badly decomposed and consists of cells and vessels much eroded, 
leaving fragments of both intermixed with apparently unchanged cells 
and vessels. This partial destruction of the spring wood causes it to 
separate readily into circular sheets along these lines of weakness. 
The next stage of the rot going inward toward the center of the tree 
is the almost complete change of the summer-wood fibers and tracheids 
into a yellowish white cellulose. Under the microscope the rotten wood 
is seen to consist of delignified wood fibers intermixed with the remnants 
of the spring wood and of nearly unchanged medullary rays, while the 
entire mass of rotted wood is ramified by large, colorless, thick-walled, 
