The Collaborative International Dictionary of English v.0.48:

Ling \Ling\, n. [Icel. lyng; akin to Dan. lyng, Sw. ljung.]
   (Bot.)
   Heather (Calluna vulgaris).
   [1913 Webster]

   Ling honey, a sort of wild honey, made from the flowers of
      the heather. --Holland.
      [1913 Webster] Linga