cockle-bur

from WordNet (r) 3.0 (2006)

cockle-bur
    n 1: any coarse weed of the genus Xanthium having spiny burrs
         [syn: {cocklebur}, {cockle-bur}, {cockleburr}, {cockle-
         burr}]

from The Collaborative International Dictionary of English v.0.48

Cocklebur \Coc"kle*bur`\, n. (Bot.)
   A coarse, composite weed, having a rough or prickly fruit;
   one of several species of the genus {Xanthium}; -- called
   also {clotbur}.
   [1913 Webster]