beggars lice

from The Collaborative International Dictionary of English v.0.48

Beggar's lice \Beg"gar's lice`\ (Bot.)
   The prickly fruit or seed of certain plants (as some species
   of {Echinospermum} and {Cynoglossum}) which cling to the
   clothing of those who brush by them.
   [1913 Webster]