R: Justice League Europe #37 (April 1992), art by Ron Randall and Murphy Anderson
(Click picture to giant-sequoia-size)
Addendum on 8/3/09: Check out this other man-to-tree-amorphosis sent in by illustrious blogger and my pal Sleestak, he of the check-it-out Lady, That's My Skull blog!:
Fantastic Stories of Imagination Volume 11, Number 12 (December 1962), art by Robert Adragan
Hmm, December 1962. I know there's a long lead time on magazines and comics, but d'ya think cover artist Adragan coulda been influenced by the 2/62 JLA cover? Hmmmmmmmmm!
Thanks so much and a tip o' the nose ring to ya, Sleestak! Consider yourself the honored winner of The Hayley Mills Bull-Prize!