The Collaborative International Dictionary of English v.0.48:

Cockspur \Cock"spur\, n. (Bot.)
   A variety of Crat[ae]gus, or hawthorn (Crat[ae]gus
   Crus-galli), having long, straight thorns; -- called also
   Cockspur thorn.
   [1913 Webster]

WordNet (r) 3.0 (2006):

cockspur
    n 1: widely grown stout Old World hay and pasture grass [syn:
         orchard grass, cocksfoot, cockspur, Dactylis
         glomerata]
    2: small spiny West Indian tree [syn: cockspur, Pisonia
       aculeata]