Wood comes in different colors and strengths depending on the kind of tree it came from, with most dark woods being from harder trees. Wood comes in two varieties: hardwood and softwood. Wood from pine and evergreen type trees is considered softwood, while wood from other kinds of trees are called hardwoods. Trees that take longer to grow, like mahogany trees, make dark, dense and stronger wood than a tree like a balsa which grows faster and is not hard or dark. Balsa is good for models, while mahogany wood is good for furniture. The bottom line is that dark woods are stronger if the dark color is caused by the density of the wood in the tree.