Accessory uses such as public utility installations, walks, driveways, curbs, retaining walls, mailboxes, nameplates, lampposts, bird baths and structures of like nature are permitted in any required front, side or rear yard. Open fences, lattice work, screens, hedges or walls not more than seven (7) feet in height and private swimming pools surrounded by a fence at least forty-eight (48) inches high may be located in the required side or rear yard and a hedge, open fence or wall maintained so as to not exceed forty-two (42) inches in height or chain link fence clear of all vegetation or obstruction at forty-eight (48) inches in height may be located in any front yard. Trees, shrubs, flowers or plants may be permitted in any required front, side or rear yard except that vision clearance on corner lots shall be provided when required.