Many plants that were once considered alien and invasive have turned out to be indigenous. We owe this knowledge to the botanical archaeology conducted on fire pits and midden mounds, as well as cores taken on lake bed sediments. There is no definitive list of all the plants that were here in North America before contact. However, a truly invasive plant is often easy to recognize. A truly invasive plant quickly crowds out other plants and reduces diversity, over a season or over a number of years. And it does it, right before your eyes. Plants that quickly colonize soil that has been bared for any reason, such as mud or landslides, floods, or fires; even plants those plants that form near monocultures on hillsides or meadows are not necessarily invasive or alien plants. Be sure to do your homework before you undertake or participate in any plant eradication efforts.
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