The Collaborative International Dictionary of English v.0.48:

Milk vetch \Milk" vetch`\ (Bot.)
   A leguminous herb (Astragalus glycyphyllos) of Europe and
   Asia, supposed to increase the secretion of milk in goats.
   [1913 Webster]

   Note: The name is sometimes taken for the whole genus
         Astragalus, of which there are about two hundred
         species in North America, and even more elsewhere.
         [1913 Webster]

WordNet (r) 3.0 (2006):

Astragalus glycyphyllos
    n 1: European perennial [syn: wild licorice, wild liquorice,
         Astragalus glycyphyllos]