Trees of the birch family include birches, hornbeams, hophornbeams (which are located in northern climates around the world), and alders, whose growing area extends south to the Andes. More than 50 species exist in the birch family, including the hazelnut shrub, which is native to North America. The trees are recognizable because both the male and female flowers, known as catkins, appear on the same tree.
Birch tree species include the European white birch, which is found throughout Europe and Asia and is recognizable for its white bark and hairless twigs, according to National Geographic's "Field Guide to the Trees of North America." Other species include the river birch, which is the only birch that grows in the American Southeast; paper birch, which is found in Canada and northern parts of the United States and whose pink-white bark was used by Native Americans to cover their canoes; yellow birch, named for its fall colors and Virginia birch, which has dark bark.
Hornbeams and Hophornbeams
Species of hornbeams include the American hornbeam, which is considered a small tree, according to National Wildlife Federation's "Field Guide to Trees of North America," and the European hornbeam, which is much larger than the American type, and is found in southwest Asia as well as Europe.
Types of hophornbeams include the Eastern hophornbeam, which is a small tree found on dry, gravelly slopes; Knowlton's hophornbeam, found in the American Southwest, especially the Grand Canyon; and Chisos hophornbeam, which is only found in Big Bend National Park in Texas.
Species of alder include the white alder, which is found in the mountains in Europe, according to "Trees," by Allen J. Coombes; the Italian alder, found in deciduous woods in the mountains of Italy; the common alder, found throughout Europe, North Africa and West Asia near rivers; and the red alder, which is found in Western North American along riverbanks and in canyons.