(1) Trees whose trunks stand partly on the land of two or more coterminous owners belong to them in common. (2) Trees whose trunks stand wholly upon the land of one owner belong exclusively to that landowner, although their roots grow into the land of another.
Trees On Or Near Boundary
Mont. Code Ann. § 70-16-204, under Adjoining Landowners and Boundaries -- Fences.
Mont. Code Ann. § 70-16-204