def root(force_reload=nil)
      @root = nil if force_reload
      @root ||= transaction do
        reload_boundaries
        base_class.roots.find(:first, :conditions => ["#{nested_set_column(:left)} <= ? AND #{nested_set_column(:right)} >= ?", left, right])
      end
    end
def root(force_reload=nil)
      @root = nil if force_reload
      @root ||= transaction do
        reload_boundaries
        base_class.roots.find(:first, :conditions => ["#{nested_set_column(:left)} <= ? AND #{nested_set_column(:right)} >= ?", left, right])
      end
    end
Finds the root node that this node descends from

 @param [Boolean] force_reload forces the root node to be reloaded
 @return [ActiveRecord::Base] node the root node this descends from