The Collaborative International Dictionary of English v.0.48:

Hedgerow \Hedge"row`\, n.
   A row of shrubs, or trees, planted for inclosure or
   separation of fields.
   [1913 Webster]

         By hedgerow elms and hillocks green.     --Milton.
   [1913 Webster]

WordNet (r) 3.0 (2006):

hedgerow
    n 1: a fence formed by a row of closely planted shrubs or bushes
         [syn: hedge, hedgerow]