Passive plant actuation has received increasing attention from scientists, especially in context of biomimetic and smart material applications. Recently, we discovered a water-activated, shape memory twist effect in wood slivers. This shape memory twist effect in wood could inspire new smart materials for a wide range of applications, including sensors, actuators, biomedical devices, and energy harvesters. Wood slivers have many advantages over current synthetic shape memory polymers, including high stiffness and the ability to twist multiple revolutions. By constructing simple torsional pendulums from wood slivers the parameters controlling the shape memory twist effect, namely sliver size, cellulose microfibril angle, and initial equilibrium moisture content, are all studied. We propose that the wood sliver shape memory twist effect is controlled by the interplay between the hemicelluloses, whose properties are strongly moisture dependent, and lignin, which remembers the original twist state.