I gave the pine cone to the treants pretty early in the game, and now they won't let me pass to meet Kayana. I went back to the Southwoods to try to get another pine cone, but there are none. Is there any way for me to still get the information and necklace from Kayana?
This seems to be a bug. I think if you gave the pine cone to the tree on the right it may have not worked correctly. A possible work around would be to use some rubbing alcohol and light them on fire.