The Collaborative International Dictionary of English v.0.48:

Forget-me-not \For*get"-me-not`\, n. [Cf. G. vergissmeinnicht.]
   (Bot.)
   A small perennial herb, of the genus Myosotis (Myosotis
   scorpiodes, Myosotis palustris, Myosotis incespitosa,
   etc.), bearing a beautiful bright blue or white flowers, and
   extensively considered the emblem of fidelity.

   Syn: mouse ear, .
        [1913 Webster + WordNet 1.5]

   Note: Formerly the name was given to the Ajuga
         Cham[ae]pitus.
         [1913 Webster]

WordNet (r) 3.0 (2006):

Myosotis scorpiodes
    n 1: small perennial herb having bright blue or white flowers
         [syn: forget-me-not, mouse ear, Myosotis scorpiodes]