Subd. 1.   It is unlawful to erect or maintain any structure or vegetation, except flowers which do not exceed 30 inches in height within a radius of 20 feet from the corner created by the projections of the curb lines at intersecting streets. Trees are not obstructions to vision if branches are trimmed to the trunks and to a height of eight feet above the curb level or to a height of nine feet above the surface of any street. Nor shall traffic control signs or signals be considered obstructions.
   Subd. 2.   This section shall apply only to districts zoned for residential purposes.
(`80 Code, § 10.12) (Ord. 189, Second Series, passed 6-1-89) Penalty, see § 1.99