The eastern United States was originally one endless, complex deciduous forest that mixed with evergreens depending on altitude and latitude. Great Smoky Mountains National Park contains all five eastern forest types – spruce fir, hemlock, pine-oak, and northern and cove hardwood – which include over 130 species of trees. Spring wildflower and autumn hardwood color displays are a Northeast specialty.
In Florida, the Everglades is the last subtropical wilderness in the US. This vital, endangered habitat is a fresh- and salt-water world of marshes, sloughs and coastal prairies that support mangroves, cypresses, sea grasses, tropical plants, pines and hardwoods.
The grasslands of the interior plains are perhaps America’s most abused ecosystem. The 19th-century ‘sodbusters’ converted them largely to agriculture, particularly the eastern tall-grass prairies, of which less than 4% remain. The semiarid short-grass prairies have survived somewhat better, but farmers have still cultivated them for monoculture row crops by tapping the underground aquifer. Theodore Roosevelt National Park is a good destination to see America’s remaining grasslands.
The Southwest deserts are horizon-stretching expanses of sage, scrub and cacti that abut western mountain ranges, where abundant wildflowers in spring and electric-yellow quaking aspens in fall inspire pilgrimages.
West of the Cascades in wet, milder Washington and Oregon are the last primeval forests in America. These diverse, ancient evergreen stands, of which only 10% remain, contain hemlocks, cedars, spruces and, in particular, towering Douglas firs.
California, meanwhile, is famous for its two species of sequoias, or redwoods. The coast redwood is the world’s tallest tree (with the very tallest in Redwood National Park), while the related giant sequoia is the world’s biggest by volume. Sequoia National Park has the granddaddy of them all.