As per the common rule, the location and ownership of a tree is determined by the position of the trunk or body of the tree.  Generally, a tree standing on the boundary line between two landowners is considered the common property of both.  However, both landowners cannot be held as tenants in common merely becasue the trees have encroached upon the line between two properties.  Whetehr or not a tree planted wholly on the property of one landowner which subsequently grows into the common boundary of the neighboring landowner becomes the property of both owners depends upon whether both landowners treat the tree as their common property in accordance to a mutual agreement.

Some Courts are of the opinion that two neighboring landowners have ownership over the part of the tree which rests upon their side of the line, with an easement of support from the other.

In Holmberg v. Bergin, 285 Minn. 250 (Minn. 1969), the defendants challenged a decision obtained by the plaintiff ordering the removal of a tree that was found to be a nuisance.  It was contended by the property owners that the tree rested, in part, on the common boundary line and had become a boundary-line tree making the neighbors tenants in common.  They also stated that neither tenant had the right to destroy the commonly held property without consent of the other.  The court ruled that something more than the mere presence of a portion of a tree trunk on a boundary line was necessary to make the tree itself a boundary-line tree.  The court found that there was no agreement between the property owners making it a boundary-line tree.  It was also found that, by planting and maintaining the tree in question, the owners obstructed the free use and enjoyment of adjoining owners’ property making it a nuisance thus affirming the judgment of the trial court.