De Bary studied the formation of lichens, the association between a fungus and an alga. He traced the stages through which they grew and reproduced and the adaptations which enabled them to survive drought and winter. He coined the word 'symbiosis' in 1879 in his monograph as "the living together of unlike organisms". He carefully studied the morphology of moulds, yeasts, and fungi and he established mycology as an independent science. 