The Collaborative International Dictionary of English v.0.48:

Samphire \Sam"phire\ (? or ?; 277), n. [F. l'herbe de Saint
   Pierre. See Saint, and Petrel.] (Bot.)
   (a) A fleshy, suffrutescent, umbelliferous European plant
       (Crithmum maritimum). It grows among rocks and on
       cliffs along the seacoast, and is used for pickles.
       [1913 Webster]

             Hangs one that gathers samphire, dreadful trade!
                                                  --Shak.
       [1913 Webster]
   (b) The species of glasswort (Salicornia herbacea); --
       called in England marsh samphire.
   (c) A seashore shrub (Borrichia arborescens) of the West
       Indies.
       [1913 Webster]

   Golden samphire. See under Golden.
      [1913 Webster]

WordNet (r) 3.0 (2006):

samphire
    n 1: fleshy maritime plant having fleshy stems with rudimentary
         scalelike leaves and small spikes of minute flowers;
         formerly used in making glass [syn: glasswort,
         samphire, Salicornia europaea]