Here are the roots to my tree.  I first started out with three roots (one of them being to the trunk) and after I glued them, it proved to be not strong enough to hold up my tree.  The fourth one that you see is really a rainbow (it was added on to the same time for support).  The largest roots (with the longest base) were added on much later.  I glued them to the blue area (which is supposed to represent Earth) once the sculpture was finished.  Above, the roots were only posed so I would know where to add them on before I glued them on.  I then painted them purple and gold for color.  The lighter purple that you see was a leftover purple that I made months ago, while the darker one was a store-bought purple (which is now my favorite purple color to paint with.)