Rosa multiflora is considered an invasive species in almost every state and should no longer be sold due to the thickets that prevent wildlife from using pastures and because it will suppress native plants that wild life need. It will spread not just by roots and branches that touch the ground and root but also by seeds that can be spread to forest and pastures by wild life. Contact your state extension agency for help laws specific to your state about this invasive species. Keep growing - but not invasive plants, Marianne Binetti