The Collaborative International Dictionary of English v.0.48:

Spinny \Spin"ny\, n.; pl. Spinnies. [OF. espinaye,espinoye,
   espinei, espanoi, F. ['e]pinaie, from L. spinetum a thicket
   of thorns, fr. spina a thorn. See Spine.]
   A small thicket or grove with undergrowth; a clump of trees.
   [Written also spinney, and spinny.]
   [1913 Webster]

         The downs rise steep, crowned with black fir spinnies.
                                                  --C. Kingsley.
   [1913 Webster]