I might be able to help you with this, seeing as it can be done with a simple DBC edit.
Since it's not christmas anymore, I won't make the patch for you, unless you don't understand my advice.
So here's what you have to do, this is exactly what I do each time I want to do an edit such as this;
1.Open MWCS and open up Base-engb2.MPQ
2. in the folder DBFilesClient, find and extract CreatureDisplayInfo.DBC (don't forget to copy the treepath of it).
3.still in MWCS use the search bar on the DBC (top right hand corner I believe) and search for Dryad, (considering you're looking for the model used by the NPC Tarindrella, it should be the first one that comes up bhighlightd blue) and type down the first, sixth, seventh and eighth field in the DBC for the dryad (type this into Notepad or something so that it looks like this;(the things entered below aren't the actual ones I think, but some could be right, you'll have to find the correct ones yourself as this is just an example)
f1 77
f6 DryadSkin
f7 Dryadextras
f8 ArmorReflect2
4. okay, now you've got all that written down, find and open CreatureDisplayInfo in a DBC editor.
5. Scroll down to where the Tree of life form is situated, I think it's called "EntSkinBrown" or something like that.
6. type the values for the fields of the dryad you copied out earlier into the respective fields for the tree, then save.
7. go back to MWCS and create an archive.
8. click add file to archive and find the CreatureDisplayInfo you just edited.
9. before you click Ok, paste the treepath of CreatureDisplayInfo into the box, then press Ok.
10. Save and Close the archive, then copy the MPQ and paste it into your WoW's data folder (if you haven't already, re-name it patch-x.mpq)
11. Run WoW.
12. shift into your Tree form and enjoy it my friend
If you try this and it still doesn't work after a few tries, search for a better guide, if it still doesn't work then PM me and I'll make it for you... but only cos I love druids
Edit; actually considering that's your first post, you might not be able to PM people yet, so just post in here if it doesn't work, I'm logged in to this site pretty much all day
