Ontario Trees & Shrubs website

Trees and Shrubs - Native / Non-Native Species

The distinction of Native and Non-native species is sometimes not clearcut. For the purposes of this website various sources are used, such as Newcombe's Wildflower Guide and other authoritative books. Generally speaking, a species is considered to be non-native if it did not occur in the region covered by this website prior to the arrival of Europeans. But there may be exceptions.
Non-native species are also often referred to as "Alien" species.
The distinction between Native and Non-native species is important because many Non-native species are invasive and alter the ecosystem of an area. They may crowd out native plants. Animals, not being familiar with the foreign plants, frequently will not use them for food or even shelter. So the impact of the Non-native species extends well past their simple presence in an area.
For more information about Non-native species, please visit the Earth Caretaker website.