The Collaborative International Dictionary of English v.0.48:

Saw palmetto \Saw" pal*met"to\
   See under Palmetto.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Palmetto \Pal*met"to\, n. [Dim. of palm the tree: cf. Sp.
   palmito.] (Bot.)
   A name given to palms of several genera and species growing
   in the West Indies and the Southern United States. In the
   United States, the name is applied especially to the
   Cham[ae]rops Palmetto, or Sabal Palmetto, the cabbage
   tree of Florida and the Carolinas. See Cabbage tree, under
   Cabbage.
   [1913 Webster]

   Royal palmetto, the West Indian Sabal umbraculifera, the
      trunk of which, when hollowed, is used for water pipes,
      etc. The leaves are used for thatching, and for making
      hats, ropes, etc.

   Saw palmetto, Sabal serrulata, a native of Georgia, South
      Carolina, and Florida. The nearly impassable jungle which
      it forms is called palmetto scrub.
      [1913 Webster]

WordNet (r) 3.0 (2006):

saw palmetto
    n 1: small hardy clump-forming spiny palm of southern United
         States [syn: saw palmetto, scrub palmetto, Serenoa
         repens]