The Collaborative International Dictionary of English v.0.48:

Starwort \Star"wort`\ (st[aum]r"w[^u]rt`), n. (Bot.)
   (a) Any plant of the genus Aster. See Aster.
   (b) A small plant of the genus Stellaria, having
       star-shaped flowers; star flower; chickweed. --Gray.
       [1913 Webster]

   Water starwort, an aquatic plant (Callitriche verna)
      having some resemblance to chickweed.

   Yellow starwort, a plant of the genus Inula; elecampane.
      [1913 Webster]

WordNet (r) 3.0 (2006):

starwort
    n 1: low-growing north temperate herb having small white star-
         shaped flowers; named for its alleged ability to ease sharp
         pains in the side [syn: stitchwort, greater stitchwort,
         starwort, Stellaria holostea]