Here in north-central AR we have what I think are two different types of mulberry trees. One has very yellow wood and looks similar to (but is not) osage orange, and the other has a darkish red heartwood that goes to a light brown between the heart and sapwood. Both are common here and as far as I know they are both mulberry, but the wood is very different and I can't seem to find any information on the proper names or how to identify one from the other. All the 'red' mulberry I've seen looks like typical mulberry when standing, but the only 'yellow' mulberry I've seen was already cut or long dead when I got to it so I haven't been able to make any sort of bark or leaf comparisons. The wood database further confuses me as it gives a fine description of 'yellow' mulberry, yet shows a picture of 'red' mulberry and doesn't make any distinction.
Are these different varieties of mulberry or does the wood change color with age/size/location/day-of-the-week? Can anyone shed some light on this mystery for me?