An interlamellar lipophilic layer regulates hygroscopic movements in moss peristomes

The presence of a polyester layer in moss peristome teeth is confirmed. We named it the interlamellar lipophilic layer (ILL). The absence of the ILL was revealed in three of the 14 species investigated. We confirm that hygroscopic movements occur when the ILL is present or absent. When the ILL is present the peristome teeth remain erect, whereas when it is absent the teeth are reflexed. These findings led us to hypothesize that the ILL influences the amplitude of movements rather than causing them, playing a regulatory role in the gradual dispersal of spores. The species that lacked the ILL were xerophytic, which may represent a novel spore dispersal strategy.