Lichens are often strikingly colored, and their pigments are often extracted and used as natural dyes. The traditional method of manufacturing Scotland’s famous tweeds made use of fungal dyes; synthetic dyes are now commonly used. Orchil, used to dye woolens, is a pigment produced specifically by lichens. In addition, several species of the lichen Rocella (from Africa) were used to produce litmus, a widely used acid-base (pH) indicator.