It was recently pointed out to me that the wood of Box Elder trees (
Acer negundo) often exhibits a reddish stain. I was curious to find out what caused it. After some research, I learned that typically, the stain has been attributed to the fungus
Fusarium reticulatum, but that
research done at the U of MN has shown that the stain is not associated with any particular species of fungus. Instead the stain is likely a result of some compound produced by the tree to protect tissue after it is compromised in some fashion.
What actually causes the stain was undetermined by the study; the compound is broken down quickly after it is produced (the authors of the study speculate that it is a phenol that oxidizes to produce the stain, but that detail will be left to the distracted chemist to explain further).
The above picture shows a box elder stump with the red stain along with a network of black lines. This is know as spalting, and is attributed to fungal decay, though as far as I know, not any particular species.
Box Elder wood is not widely used since it is a relatively weak and rot-prone wood. But wood with the red stain is used by wood workers to make smaller, ornamental objects.
