The Collaborative International Dictionary of English v.0.48:

Speedwell \Speed"well\, n. (Bot.)
   Any plant of the genus Veronica, mostly low herbs with pale
   blue corollas, which quickly fall off.
   [1913 Webster]

WordNet (r) 3.0 (2006):

speedwell
    n 1: any plant of the genus Veronica [syn: veronica,
         speedwell]