If this be the correct reading (and not Long Heath) the reference is to the Heather or Common Ling (Calluna vulgaris). This is the plant that is generally called Ling in the South of England, but in the North of England the name is given to the Cotton Grass (Eriophorum). It is very probable, however, that no particular plant is intended, but that it means any rough, wild vegetation, especially of open moors and heaths.