The Collaborative International Dictionary of English v.0.48:

Algaroba \Al`ga*ro"ba\, n. [Sp. algarroba, fr. Ar. al-kharr?bah.
   Cf. Carob.] (Bot.)
   (a) The Carob, a leguminous tree of the Mediterranean region;
       also, its edible beans or pods, called St. John's
       bread.
   (b) The Honey mesquite (Prosopis juliflora), a small tree
       found from California to Buenos Ayres; also, its sweet,
       pulpy pods. A valuable gum, resembling gum arabic, is
       collected from the tree in Texas and Mexico.
       [1913 Webster] algaroth

WordNet (r) 3.0 (2006):

Prosopis juliflora
    n 1: mesquite of Gulf Coast and Caribbean Islands from Mexico to
         Venezuela [syn: algarroba, Prosopis juliflora,
         Prosopis juliiflora]