Herbaceous plants - perennial

The life cycle of perennial plants lasts longer than two years. Once established in an ecosystem these noxious weeds will continue to grow and spread, altering the composition of area unless managed. Plant infestations can alter the carbon and nitrogen cycle and make an area more susceptible to fire damage. Invasive knotweed for example will colonize a riverbank and change the structure of a river through erosion and clogged waterways. Herbaceous perennial weeds can damage wildlife habitat and even human structures such as buildings and bridges.