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.

This is a list of Non-Native species found on this site, in order by the Common Name that is used for each species on this site. Click Here for a list of Native Species.

To see all Non-Native Plants in order by Common Name → START HERE

Ailanthus (Ailanthus altissima)
Alder, European Black (Alnus glutinosa)
Barberry, European (Berberis vulgaris)
Barberry, Japanese (Berberis thunbergii)
Birch, European White (Betula pendula)
Buckthorn, Common (Rhamnus cathartica)
Buckthorn, Glossy (Frangula alnus)
Euonymus, Winged (Euonymus alata)
Ginkgo (Ginkgo biloba)
Horsechestnut (Aesculus hippocastanum)
Larch, European (Larix decidua)
Lilac, Common (Syringa vulgaris)
Locust, Black (Robinia pseudoacacia)
Maple, Norway (Acer platanoides)
Olive, Autumn (Elaeagnus umbellata)
Pine, Austrian (Pinus nigra)
Pine, Mugo (Pinus mugo)
Pine, Scots (Pinus sylvestris)
Poplar, Lombardy (Populus nigra)
Privet (Ligustrum vulgare)
Spirea, False (Sorbaria sorbifolia)
Spruce, Norway (Picea abies)
Walnut, English (Juglans regia)
Willow, Weeping (Salix babylonica)

To see all Non-Native Plants in order by Common Name → START HERE