The Collaborative International Dictionary of English v.0.48:

Impatiens \Im*pa"ti*ens\ ([i^]m*p[=a]"sh[i^]*[e^]nz), prop. n.
   [L., impatient.] (Bot.)
   A genus of plants, several species of which have very
   beautiful flowers; -- so called because the elastic capsules
   burst when touched, and scatter the seeds with considerable
   force. Called also touch-me-not, jewelweed, and
   snapweed. Impatiens Balsamina (sometimes called lady's
   slipper) is the common garden balsam.
   [1913 Webster]