The Collaborative International Dictionary of English v.0.48:

Paris \Par"is\, n. [From Paris, the son of Priam.] (Bot.)
   A plant common in Europe (Paris quadrifolia); herb Paris;
   truelove. It has been used as a narcotic.
   [1913 Webster]

   Note: It much resembles the American genus Trillium, but
         has usually four leaves and a tetramerous flower.
         [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

leopard's bane \leop"ard's bane`\ (l[e^]p"[~e]rdz b[=a]n`) n.
   (Bot.)
   A name of several harmless plants, as Arnica montana
   (Arnica acaulis syn. Doronicum acaule), Senecio
   Doronicum, and Paris quadrifolia.

   Syn: leopardbane, leopard's-bane.
        [1913 Webster +PJC]

The Collaborative International Dictionary of English v.0.48:

Herb \Herb\ ([~e]rb or h[~e]rb; 277), n. [OE. herbe, erbe, OF.
   herbe, erbe, F. herbe, L. herba; perh. akin to Gr. forbh`
   food, pasture, fe`rbein to feed.]
   1. A plant whose stem does not become woody and permanent,
      but dies, at least down to the ground, after flowering.
      [1913 Webster]

   Note: Annual herbs live but one season; biennial herbs flower
         the second season, and then die; perennial herbs
         produce new stems year after year.
         [1913 Webster]

   2. Grass; herbage.
      [1913 Webster]

            And flocks
            Grazing the tender herb.              --Milton.
      [1913 Webster]

   Herb bennet. (Bot.) See Bennet.

   Herb Christopher (Bot.), an herb (Act[ae]a spicata),
      whose root is used in nervous diseases; the baneberry. The
      name is occasionally given to other plants, as the royal
      fern, the wood betony, etc.

   Herb Gerard (Bot.), the goutweed; -- so called in honor of
      St. Gerard, who used to be invoked against the gout. --Dr.
      Prior.

   Herb grace, or Herb of grace. (Bot.) See Rue.

   Herb Margaret (Bot.), the daisy. See Marguerite.

   Herb Paris (Bot.), an Old World plant related to the
      trillium (Paris quadrifolia), commonly reputed
      poisonous.

   Herb Robert (Bot.), a species of Geranium (Geranium
      Robertianum.)
      [1913 Webster]

WordNet (r) 3.0 (2006):

Paris quadrifolia
    n 1: European herb with yellow-green flowers resembling and
         closely related to the trilliums; reputed to be poisonous
         [syn: herb Paris, Paris quadrifolia]