Summary Most lichens in general, and their phycobionts in particular, are desiccation tolerant, but their mechanisms of desiccation tolerance (DT) remain obscure. The physiological responses and cell wall features of two putatively contrasting lichen‐forming microalgae, Trebouxia sp. TR9 (TR9), isolated from Ramalina farinacea (adapted to frequent desiccation‐rehydration cycles), and Coccomyxa solorina‐saccatae ( Csol ), obtai...