The Collaborative International Dictionary of English v.0.48:

Nightshade \Night"shade`\, n. [AS. nichtscadu.] (Bot.)
   A common name of many species of the genus Solanum, given
   esp. to the Solanum nigrum, or black nightshade, a low,
   branching weed with small white flowers and black berries
   reputed to be poisonous.
   [1913 Webster]

   Deadly nightshade. Same as Belladonna
   (a) .

   Enchanter's nightshade. See under Enchanter.

   Stinking nightshade. See Henbane.

   Three-leaved nightshade. See Trillium.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Three-leafed \Three"-leafed`\, Three-leaved \Three"-leaved`\, a.
   (Bot.)
   (a) Producing three leaves; as, three-leaved nightshade.
   (b) Consisting of three distinct leaflets; having the
       leaflets arranged in threes.
       [1913 Webster]

   Three-leaved nightshade. See Trillium.
      [1913 Webster]