Nearctic realm

The Nearctic is one of the eight biogeographic realms constituting the Earth's land surface.

The Nearctic realm covers most of North America, including Greenland, Central Florida, and the highlands of Mexico. The parts of North America that are not in the Nearctic realm are Eastern Mexico, Southern Florida, Central America, and the Caribbean islands which are part of the Neotropical realm, together with South America.

The World Wildlife Fund (WWF) divides the Nearctic into four bioregions, defined as "geographic clusters of ecoregions that may span several habitat types, but have strong biogeographic affinities, particularly at taxonomic levels higher than the species level (genus, family)."

The Canadian Shield bioregion extends across the northern portion of the continent, from the Aleutian Islands to Newfoundland. It includes the Nearctic's Arctic Tundra and Boreal forest ecoregions.

In terms of floristic provinces, it is represented by part of the Canadian Province of the Circumboreal Region.

The Eastern North America bioregion includes the temperate broadleaf and mixed forests of the Eastern United States and southeastern Canada, the Great Plains temperate grasslands of the Central United States and south-central Canada, the temperate coniferous forests of the Southeastern United States and Central Florida. In terms of floristic provinces, it is represented by the North American Atlantic Region and part of the Canadian Province of the Circumboreal Region.

...
Wikipedia