Introduced species
Sweet clover (Melilotus sp.), introduced and
naturalized to the U.S. from Eurasia as a for-
age and cover crop.
A species is defined as introduced (also
known as non-indigenous, alien or exotic)
in a certain geographical area, if that area is
outside the species’ native distributional
range, and the species has arrived there by
human activity. Introduced species some-
times are damaging to the ecosystem they
are introduced into, others negatively affect
agriculture and other human uses of natural
resources or impact on the health of animals
and humans. A list of introduced species is
given in a separate article. Introduced spe-
cies and their effects on natural environ-
ments is a controversial subject and one that
has gained much scrutiny by scientists, gov-
ernments, farmers and others.
Terminology
The terminology associated with introduced
species is presently in flux for a variety of
reasons. Other terms that are used some-
times interchangeably (having the same or
similar meanings) with introduced are accli-
matized, adventive, native, naturalized, im-
migrant, non-indigenous,
and xenobiotic.
Nonetheless, distinctions can and should be
made between some of these terms.
In the broadest and most widely used
sense, an introduced species is synonymous
with non-native and therefore applies as well
to most garden and farm organisms; these
adequately fit
the basic definition given
above. However, some sources add to that
basic definition: "...and are now reproducing
in the wild",[1] which removes from consider-
ation as introduced all of those species raised
or grown in gardens or farms that do not sur-
vive without tending by people. With respect
to plants, these latter are in this case defined
as either ornamental or cultivated plants.
The following definition from the United
States Environmental Protection Agency, al-
though perhaps lacking ecological sophistica-
tion, is more typical: introduced species are
.."[s]pecies that have become able to survive
and reproduce outside the habitats where