I'm Looking For Some Research Help

Hi all,

I have a favour to ask. In my (absolutely splendiferously awesome) course on Children's Fantasy mentioned in my previous post, we have started studying the Chronicles of Earthsea. It turns out that my attitude to this particular course is to encourage my lecturers to run in fear from my opinions, basically because I know the set texts pretty well so I'm trying to wring the last drop of meaning out of them. So far my lecturers seem to know the books even better than I do, so I probably won't win, but I'm going to have fun trying. ;-)
Anyway, on to the favour. The Earthsea books are absolutely reeking with plant references, particularly in the wood that the wizards' staffs are made of. For some of them (yew, rowan, oak etc) I'm passably familiar with the pagan symbolism associated with them, but, while I have some reference texts, they're buried at the bottom of seven boxes of books. Can anyone out there suggest some good internet resources and books that the public and university libraries are likely to have?
Thanks,
Steph

*********************************
What I can pull out of memory so far (I'm treating this as a scratchpad, sorry for any errors):
Yew: Ged, the second Master Summoner, planted in graveyards, used for bows, protection from the dead, immortality
Rowan: Lebannen, protection from magic, the berries make a pentagram and I know there's heaps more
Oak: Ogion
Olive: Master Healer
Aspen: the evil wizard in Tehanu
Alder: Tenar
Hazel: Therru
The Immanent Grove is comprised of oaks, willows, chestnuts, ashes and tall evergreens, (Dragonfly, p237) plus the Tree of the Grove which is a bit like an oak and a bit like a chestnut and only grows there.