§ 155.165 PLANT SPECIES.
   (A)   Any proposed new plant material used to satisfy the requirements of this chapter shall be of a species other than those listed in the current version of the Louisville and the county prohibited plant list adopted by the Planning Commission. To the greatest extent possible, new plant material should be selected from species included in the current version of the Louisville and the county preferred plant list adopted by the Planning Commission. This list consists of species that are either native to the county or that perform particularly well in the area, or both.
   (B)   Over-dependence on a single genus may result in extensive loss due to disease, insects, or other
pests. To ensure a diversity of species within Louisville and the county’s forests, the mix of required trees and shrubs for all development proposals shall conform to the following diversification formula: 50% maximum of any single species (for example, quercus rubrum).
   (C)   Exceptions to the diversification formula shall be allowed for:
      (1)   Sites of less than two acres, if required plantings are chosen from the preferred plant list;
      (2)   Sites located within a neighborhood study or corridor study approved by the Planning Commission with street tree or landscape guidelines or sites containing a streetscape master plan approved by the Planning Commission; and
      (3)   A planned development or general development plan containing a planting plan approved prior to the effective date of this code.
(LDC § 10.4.1) Penalty, see § 155.999