The question of litter while of importance with city street trees does not matter so much in the case of highway trees, but the cottony seed from poplars is very objectionable anywhere. The longevity of a tree is important. The desire for quick results often outweighs other considerations. Many of the trees which give results such as silver maple, box elder and Carolina poplar do not last long and the effort spent on them is wasted. More time and money is needed within a short time to remove and replace such trees. It is better to plant well in the first place. Trees do not grow at the same rate throughout their life. They usually grow slowly at first and then fairly rapidly between the tenth and thirteenth years, after which the rate of growth usually falls off gradually. If small trees, about ten feet high are used for planting they should reach the following sizes in twenty years on favorable soil:
| American elm | 18 | inches |
| Basswood | 15 | " |
| Chestnut | 12 | " |
| Hard maple | 11 | " |
| Red oak | 11 | " |
| Pin oak | 9 | " |
| White ash | 9 | " |
| Black walnut | 8 | " |
| Hackberry | 7 | " |
Certain trees such as the horse chestnut and the evergreens generally appear to better advantage alone or in groups while others like the elms, maples and box elder show to fine advantage in long rows. It is doubtful if the planting of windbreaks along the highways is advisable. Windbreaks are sometimes planted with the idea of preventing the drifting of snow but the snow will collect and form great drifts on the leeward side of a windbreak and the shade from the windbreak may prevent the snow from melting so rapidly. Hedges may be used, however, to prevent the shifting of sand or the erosion of steep slopes.
The highways offer excellent opportunities for nut production and such trees as the black walnut and hickories may often be used to advantage. The presence of birds may be encouraged by planting hackberry and other trees or shrubs of which they are fond.
The Michigan Agricultural College was authorized by the Legislature to raise trees for roadside planting. The College is raising red oak, black walnut, oriental sycamore, sugar maple, elm, hackberry, snowdrop tree, Juneberry, hickory, European larch, Norway maple and box elder for this purpose. Other trees may be added to the list from time to time.
In addition to the planting of trees we need also the proper care of those already planted or growing naturally along the roads. The commonest source of injury is due to improper pruning for telephone lines. A great many trees are badly injured in this way. We already have a large investment in highway trees and it is only the part of wisdom to protect this investment.
Michigan has started active work in highway planting and we hope in a few years to be able to point with pride to our highways, not only because of the good roadbeds but also because of the trees and shrubs that line those roads.
The President: Is there any discussion on Prof. Chittendon's paper? If not, it will be received and filed in the proceedings.
It is now near the noon hour and I think it would be well to have Mr. Jones or Mr. Rush state what program has been arranged for this afternoon.
MR. J. F. Jones: I believe the plan is to get dinner here, and then to go to our nursery at Willow Street. From there some machines will take the parties who do not have conveyances, around to other points.