The Collaborative International Dictionary of English v.0.48:

Flower-fence \Flow"er-fence`\, n. (Bot.)
   A tropical leguminous bush (Poinciana pulcherrima, or
   C[ae]salpinia, pulcherrima) with prickly branches, and
   showy yellow or red flowers; -- so named from its having been
   sometimes used for hedges in the West Indies. --Baird.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Poinciana pulcherrima
    n 1: tropical shrub or small tree having showy yellow to orange-
         red flowers; sometimes placed in genus Poinciana [syn:
         pride of barbados, paradise flower, flamboyant tree,
         Caesalpinia pulcherrima, Poinciana pulcherrima]