The Collaborative International Dictionary of English v.0.48:

Stavesacre \Staves"a`cre\ (st[=a]vz"[=a]`k[~e]r), n. [Corrupted
   from NL. staphis agria, Gr. stafi`s dried grape + 'a`grios
   wild.] (Bot.)
   A kind of larkspur (Delphinium Staphysagria), and its
   seeds, which are violently purgative and emetic. They are
   used as a parasiticide, and in the East for poisoning fish.
   [1913 Webster]