Lord of the White Tree

[Cameron Waite]

This may be a silly question but in Rotk when Gimli is speaking he says something like he will continue in the war for the honor of the folk of the lovely mountain or in other words his people. Then Legolas says that he too will continue for the folk of the Great Wood and "for the love of the Lord of the White Tree." Who is this lord? celeborn? And if so why does Legolas show allegiance to him being a mirkwood elf and son of King Thranduil? Or is it Aragorn who will soon be the Lord of Minas Tirith and the White Tree that blooms there? Anyone?
oh and by the way this is found in the Last Debate chapter of Rotk.