(1) Category 4 plant species are plants that are invasive and may cause significant economic or environmental impacts if allowed to become established in Montana. Research and monitoring for Category 4 plant species may result in future listing as a Category 1, 2, or 3 noxious weed in Montana. Plant species designated as a Category 4 plant are prohibited from sale in or into Montana.

(2) The following are designated as Category 4 noxious weeds:

(a) Scotch broom (Cytisus scoparius).