I can't get over thinking of James Potter, or even his son Harry, as representative of a Holly Tree (not sure about their wands, but whatever). According to one of the wand wood/celtic trees sites, it characterizes Holly as a noble and charismatic tree, full of leadership potential, and I see that as something both father and son have in common. Furthermore, it also characterizes them as ambitious and determined, always ready to overcome obstacles, which James clearly showed in his standing up against Voldemort, and Harry likewise in his series-long saga against the same. It also says that Holly can be "generous, kind and affectionate", which is clearly true for both, too, underneath their exteriors. I might even add that I think it's a great plant to represent Godric Gryffindor himself; noble, strong, and kind, but also apt to get lazy.

Silver//Gryffindor