I did not intend to wake up this morning and ask about the specifics of wood, but it was strangely bothering me, so I thought I'd ask!

I'm just curious if anyone knows the origin of nightwood, because I sure don't, and it's just weird that you find these purple stacks of wood in Craglorn/Rivenspire/etc., and there are no trees around similar to how it looks. Am I just missing something/don't know the lore, or has it not been addressed yet?