The Penquis Virtual Nature Center provides a list of hardwood trees that includes species of alder, poplar, birch, beech, oak, cherry, sumac, maple and ash. Each tree species has its own distinct characteristics, but all of them are classified as hardwood because of some distinguishing features.
Hardwood trees are also called broadleaf trees because of the broad and flat leaves they possess, as opposed to the needle-like foliage of conifers. Most hardwoods are deciduous, which means they shed leaves annually depending on the season. Exceptions to this classification are the magnolia and the American holly, which flower all year round. Although the name suggests that hardwoods should be heavy and hard to cut because of their harder or denser wood material, it is not so for all species. Balsa wood is soft and not dense, in fact, it is softer than many softwood trees, yet it is classified as a hardwood.
The scientific distinction between hardwood and softwood trees is that hardwoods are classified as "angiosperms," while softwoods are "gymnosperms." Angiosperms produce seeds with a protective covering or shell, whereas gymnosperm seeds are dispersed without such a shell. Hardwood seeds include fruits like oranges and apples, as well as shelled seeds like acorns and walnuts.