The Collaborative International Dictionary of English v.0.48:

Sparrowgrass \Spar"row*grass`\, n. [Corrupted from asparagus.]
   Asparagus. [Colloq.] See the Note under Asparagus.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Asparagus \As*par"a*gus\ ([a^]s*p[a^]r"[.a]*g[u^]s), n. [L., fr.
   Gr. 'aspa`ragos, 'asfa`ragos; cf. sparga^n to swell with sap
   or juice, and Zend [,c]paregha prong, sprout, Pers. asparag,
   Lith. spurgas sprout, Skr. sphurj to swell. Perh. the Greek
   borrowed from the Persian. Cf. Sparrowgrass.]
   1. (Bot.) A genus of perennial plants belonging to the
      natural order Liliace[ae], and having erect much
      branched stems, and very slender branchlets which are
      sometimes mistaken for leaves. Asparagus racemosus is a
      shrubby climbing plant with fragrant flowers.
      Specifically: The Asparagus officinalis, a species
      cultivated in gardens.
      [1913 Webster]

   2. The young and tender shoots of Asparagus officinalis,
      which form a valuable and well-known article of food.
      [1913 Webster]

   Note: This word was formerly pronounced sparrowgrass; but
         this pronunciation is now confined exclusively to
         uneducated people.
         [1913 Webster]

   Asparagus beetle (Zool.), a small beetle (Crioceris
      asparagi) injurious to asparagus.
      [1913 Webster]