Hardwoods are deciduous trees and broadleaf evergreen trees, and all are angiosperms (flowering plants) that produce seeds or enclosed nuts, whereas softwoods are conifers (cone bearing seed plants). As their name implies, the wood from hardwood trees is typically harder than that from softwood trees, but there some exceptions, most notably balsa wood, which is the lightest of any commercially available wood. Hardwoods have a more complex structure than softwoods and thus often have a much slower growth rate. They are also much more varied than softwoods, with about a hundred times more species.