Also 8 crottel, crotal. [a. Gaelic crotal, crotan a lichen, esp. one used in dyeing.] A name given in Scotland to various species of lichen used in dyeing: cf. CUDBEAR.
1778. J. Lightfoot, Flora Scot. (1789), 818. Lichen omphalodes. Dark purple Dyer’s Lichen. Cork or Arcell Anglis, Crotal Gaulis.
1794. Statist. Acc. Scot., XII. 113. It [cudbear] was known as a dye-stuff in the Highlands by the name of cookes or crottel some hundred years ago.
1861. H. Macmillan, Footnotes fr. Page Nature, 116. The dyes she herself prepares, by simply boiling in water … various species of crotal or lichens.
1881. in D. H. Edwards, Mod. Scot. Poets, Ser. III. 399. When ither dykes Wi’ crottle are grown grey.
