22 MISSOURI BOTANICAL GARDEN. 
southern shore of Long Island, N. Y., where it destroyed 
the wood of many of the fine old trees, which form one of 
the attractive features of the boulevards.* Every severe 
windstorm breaks off some of the large branches of affected 
trees, and oftentimes the entire crown, so that the whole 
tree must be removed. 
Polyporus rimosus attacks the locust after the trees 
have formed some heartwood in the larger branches, 7. e. 
when the trees are about six inches in diameter. From 
this time on one will find the mycelium of the fungus grow- 
ing in the heartwood, and with increasing frequency as the 
trees grow older. Infection takes place through older 
branches, and through the tunnels made by the locust 
borer. Wounds are frequent in older trees because of the 
extremely brittle nature of the branches. The fresh 
wounds are favorable points for the germination of the 
spores, and it is an easy matter to find all stages, from 
trees recently infected, to trees where the whole side of a 
trunk has evidently been infected from one branch. 
The wood of the locust is very hard and resistant, and 
has been used for many years to such an extent that it ranks 
among the most valuable timbers. The following descrip- 
tion of the wood is given by Sargent:f ‘* The wood is 
heavy, exceedingly hard and strong, close grained and very 
durable in contact with the ground. It is brown or more 
rarely light green with pale yellow sapwood composed of 
two or three layers of annual growth only; . . . The spe- 
cific gravity of the absolutely dry wood is 0.7333, a 
cubic foot weighing 45.70 pounds.’’ 
Several rows of very large ducts mark the beginning of 
the spring wood. These ducts are remarkable for the large 
number of thylloses which completely fill the lumen; this 
feature distinguishes the wood from that of the closely 
* The writer is indebted to Mr. A. Wagstaff of Babylon, L. I., for 
permission to cut an affected tree on his grounds. 
+ Sargent, C. S. Silva of North America. 8: 40. 1892. 
