No person shall plant on any public property the following trees: poplar, willow, conifer, cottonwood, fruit tree, nut tree or ailanthus, except that tree species commonly found in riparian areas and wetlands, including but not limited to poplar and willow, may be planted in riparian areas and wetlands if part of approved restoration or enhancement plans. No person shall plant willow, cottonwood or poplar trees anywhere in the City unless the City Manager approves the site as one upon which the tree roots will not interfere with a public sewer or private lateral.