The Collaborative International Dictionary of English v.0.48:

cassie \cassie\ n.
   a type of tropical American thorny shrub or small tree
   (Acacia farnesiana); it bears fragrant yellow flowers used
   in making perfumery.

   Syn: huisache, mimosa bush, sweet wattle, sweet acacia,
        scented wattle, flame tree, Acacia farnesiana.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

cassie
    n 1: tropical American thorny shrub or small tree; fragrant
         yellow flowers used in making perfumery [syn: huisache,
         cassie, mimosa bush, sweet wattle, sweet acacia,
         scented wattle, flame tree, Acacia farnesiana]