ocr: Lichens to dye for An arsenal of nearly 600 chemicals unique to lichens helps them sur- vive in marginal environments and ward off attacks by bacteria, other fungi, and grazing herbivores. Called lichen substances, these pigments, toxins, and antibiotics have made lichens very usefulto people in diverse cultures, espe- cially as a source of dyes and medicines. The warm browns in rugs made by members of the Ramah Navajo Weavers Association come from boiling the vagrant lichen Xanthoparmelia chlorochroa, seen ina basket with a skein of dyed wool (left). The lichens once used to dye Scottish Harr ...
