(The). The Guelder rose (q.v.).
Wayfaring Tree' What ancient claim Hast thou to that right pleasant name? Was it that some faint pilgrim came Unhopedly to thee, In the brown desert's weary way, Midst thirst and toil's consuming sway, And there, as `neath thy shade he lay, Blessed the Wayfaring Tree?
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894