Mich. Comp. Laws § 247.242
The state highway commissioner is hereby authorized and empowered as a part of the maintenance of trunk line and federal aided roads to protect trees and shrubs set out along and within the limits of such roads and to set out such trees and shrubs as may be furnished to him by the Michigan agricultural college, the department of conservation, or by any other state department or institution, or obtained from neighboring lands without cost, for the use and benefit of the public. The care of such trees shall be deemed to be a part of the road maintenance work. Boards of county road commissioners and township highway authorities shall likewise have power to set out and maintain such trees along, and within the limits of, roads under their respective jurisdictions.
MCL 247.242