The city shall have the right to plant, prune, maintain and remove trees, plants and shrubs within the lines of all streets, alleys, avenues, lanes, squares and public grounds, as may be necessary to insure public safety or to preserve or enhance the symmetry and beauty of the public grounds. The city may remove, or cause or order to be removed, any tree or part thereof which is in an unsafe condition or which by reason of its nature is injurious to sewers, electric power lines, gas lines, water lines or other public improvements or is affected with any injurious fungus, insect or other pest. This section shall not prohibit the planting of street trees by adjacent property owners.
(‘88 Code, § 15.207)