Do you have any junipers near your oak? Junipers are notorious for
being gall carriers. The ones here in NJ seem to affect nearby
crabapples rather fiercely and your photos is quite similar to what
afflicts by mine.

Boron


Well actually it isn't "my" oak tree. It is in the woods. I have no
earthly idea what a juniper looks like. I am a photographer and my main
interest is in nailing down the taxonomy of whatever that lil' bugger
on the leaf is.

thanks,

york