The Collaborative International Dictionary of English v.0.48:

Chufa \Chu"fa\, n. [Sp.] (Bot.)
   A sedgelike plant (Cyperus esculentus) producing edible
   tubers, native about the Mediterranean, now cultivated in
   many regions; the earth almond.
   [1913 Webster]

WordNet (r) 3.0 (2006):

chufa
    n 1: European sedge having small edible nutlike tubers [syn:
         chufa, yellow nutgrass, earth almond, ground
         almond, rush nut, Cyperus esculentus]