The Collaborative International Dictionary of English v.0.48:

Halesia \Ha*le"si*a\ (h[.a]*l[=e]"zh[i^]*[.a]), n. [NL.] (Bot.)
   A genus of American shrubs containing several species, called
   snowdrop trees, or silver-bell trees. They have showy,
   white flowers, drooping on slender pedicels.
   [1913 Webster]