By expert estimates, there are over 20,000 species of flowering plants
in North America, belonging to about 300 different families. Those that
grow in the wild or on their own, without cultivation, are called wildflowers.
Wildflowers indigenous to the continent are called “natives”. Others, which may
be quite common, but not indigenous, have been introduced from some
other part of the world and are referred to as “naturalized.” Both types share
one common distinction: They are equipped to grow on their own in nature.