I'm no expert, but our buns enjoy the leaves and twigs of the cherry tree that grows in our garden, and as far as I know all the native apple, pear, plum etc twigs and leaves are all fine. A couple of days ago someone posted a useful link that was very comprehensive as to what rabbits can and can't have. I wish now I'd pasted it into my favourites so I could find it again. Perhaps someone will see this and re-post it!