Phillips—Hail Injury on Forest Trees. 53 
eatalpa with the exception that the bark wounds on 
catalpa were much more irregular because of the fibrous 
nature of the bark. 
The deepest bark wounds on any species were found on 
the cottonwood and box elder. This was due to the soft, 
smooth nature of the bark which extends over compara- 
tively large branches, while in such trees as catalpa the 
bark matures rapidly. It was not infrequent to see 
branches of cottonwood 3 to 4 inches in diameter with 
wounds an inch broad and several inches long. Cotton- 
wood was about one-half defoliated; the characteristic 
injury consisting of riddled leaves which consequently 
lost their function and were shed by the tree. A peculiar 
character of the injury to the limbs consisted of wounds 
bridged over by dead cortical strands of fibrous bark. 
It is thought that the force of the hail was sufficient to 
injure the cambium without entirely destroying the bark. 
The possibility of fungus action was considered but since 
no trace of fungi was found in such areas it was thought 
improbable that the injury was due to such a cause. 
Honey locust suffered from defoliation but had only 
slight injury to the wood. Black walnut was in most cases 
entirely defoliated. The bark was wounded slightly more 
than honey locust but not so much as box elder or cotton- 
wood. Silver maple had slight injury both to the leaves 
and the bark. Green ash leaves were less injured than 
black walnut while the bark was injured about the same. 
Russian olive leaves were scarcely affected and the bark 
showed injury only in rare cases. Bur oak had no ap- 
preciable injury to the bark and only a few leaves were 
partially lacerated. 
Box elder suffered more from defoliation than did 
cottonwood, but on the other hand more leaves were shed 
and fewer lacerated. The wounds on the young wood were 
as severe as on cottonwood. American elm suffered mod- 
erately from defoliation and laceration, but had only rare 
injury to the bark. English elm showed still less effect 
on leaves and wood than American elm. White willow 
suffered worse than sand-bar willow in both bark and 
