De Bary also studied the formation of lichens which are the result of an association between a fungus and an alga. He traced the stages through which they grew and reproduced and the adaptations that enabled them to survive drought and winter. He coined the word "symbiosis" in 1879 in his monograph "Die Erscheinung der Symbiose" (Strasbourg, 1879) as "the living together of unlike organisms". He carefully studied the morphology of molds, yeasts, and fungi and basically established mycology as an independent science.