Ecology/Biology

          Noxious weeds are usually alien to the area, and not part of the "native" plant community. The life cycle and competitiveness of a weed determine how serious its threat to the native plant community will be. In other words, it is the biology and ecology of a weed that sets it apart as an invading species.

          Another factor that influences the ability of a weed to compete against local plants and dominate an area is their lack of natural control agents. A biological control agent is any living thing that can hinder or control the growth of a plant species. This may come in the form of animal, insect, or plant diseases that feed on or infect the plant. When alien weeds came to the United States, they left most, if not all, of their control agents behind. On the other hand, native plants must cope with the pressures of numerous control agents, native to their own environment. Its like making all of the native plant's walk down the path of life with illness and injury, while strong invading plants have few of these hardships. Who will win the race, or in this case, who will increase in population size and strength and who will not?