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