The Collaborative International Dictionary of English v.0.48:

Woodruff \Wood"ruff`\, Woodroof \Wood"roof`\, n. [AS. wudurofe.
   See Wood, n., and cf. Ruff a plaited collar.] (Bot.)
   A little European herb (Asperula odorata) having a pleasant
   taste. It is sometimes used for flavoring wine. See Illust.
   of Whorl.
   [1913 Webster]