Reed canary grass is a native in the northern United States.  Why is this considered an invasive species that poses a major threat to wetland areas?

1. Human activities and land-use practices have changed allowing this species to persist and increase in numbers.

2. The European reed canary grass has displaced the American reed canary grass.

3. Inter-breeding between the European and native varieties produced an invasive form.

4.  Reed canary grass naturally evolved to be a more competitive species.