crottle

1. (orignally Scotland) Any of various lichens gathered for dyeing, especially those of the genus Parmelia.Examples: "It was known and uſed as a dye-ſtuff in the Highlands of Scotland by the name of corkes or crottel, ſome hundred years ago."; "Not that crotal and white was as humdrum as a simple definition of it as ‘brown and white’ implies. Crotal was the grey lichen which, over hundreds of years, had grown over the moorland rocks particularly"; "Parmelia omphalodes and P. saxitilis, the “crottles” used traditionally in Britain and Ireland, are sub-alpine lichens in North America."