The Collaborative International Dictionary of English v.0.48:

Hartwort \Hart"wort`\ (h[aum]rt"w[^u]rt`), n. (Bot.)
   A coarse umbelliferous plant of Europe (Tordylium maximum).
   [1913 Webster]

   Note: The name is often vaguely given to other plants of the
         same order, as species of Seseli and Bupleurum.
         [1913 Webster]