The Collaborative International Dictionary of English v.0.48:

horsebean \horsebean\ n.
   1. The seed of the broad-bean plant.

   Syn: broad bean, fava bean.
        [WordNet 1.5]

   2. A large shrub or shrubby tree (Parkinsonia aculeata)
      having sharp spines and pinnate leaves with small
      deciduous leaflets and sweet-scented racemose
      yellow-orange flowers; grown as ornamentals or hedging or
      emergency food for livestock; originating in tropical
      America but naturalized in the Southern U. S.

   Syn: Jerusalem thorn, Parkinsonia aculeata.
        [WordNet 1.5]

The Collaborative International Dictionary of English v.0.48:

Jerusalem \Je*ru"sa*lem\ (j[-e]*r[udd]"s[.a]*l[e^]m), n. [Gr.
   'Ieroysalh`m, fr. Heb. Y[e^]r[=u]sh[=a]laim.]
   The chief city of Palestine, intimately associated with the
   glory of the Jewish nation, and the life and death of Jesus
   Christ.
   [1913 Webster]

   Jerusalem artichoke [Perh. a corrupt. of It. girasole i.e.,
      sunflower, or turnsole. See Gyre, Solar.] (Bot.)
   (a) An American plant, a perennial species of sunflower
       (Helianthus tuberosus), whose tubers are sometimes used
       as food.
   (b) One of the tubers themselves.

   Jerusalem cherry (Bot.), the popular name of either of two
      species of Solanum (Solanum Pseudo-capsicum and
      Solanum capsicastrum), cultivated as ornamental house
      plants. They bear bright red berries of about the size of
      cherries.

   Jerusalem oak (Bot.), an aromatic goosefoot (Chenopodium
      Botrys), common about houses and along roadsides.

   Jerusalem sage (Bot.), a perennial herb of the Mint family
      (Phlomis tuberosa).

   Jerusalem thorn (Bot.), a spiny, leguminous tree
      (Parkinsonia aculeata), widely dispersed in warm
      countries, and used for hedges.

   The New Jerusalem, Heaven; the Celestial City.
      [1913 Webster]

WordNet (r) 3.0 (2006):

Parkinsonia aculeata
    n 1: large shrub or shrubby tree having sharp spines and pinnate
         leaves with small deciduous leaflets and sweet-scented
         racemose yellow-orange flowers; grown as ornamentals or
         hedging or emergency food for livestock; tropical America
         but naturalized in southern United States [syn: Jerusalem
         thorn, horsebean, Parkinsonia aculeata]