Before revision: The possible theories for plant nutations Over the last century, studies on plant nutations gave rise to three main theories about their origin: The theory of the "internal oscillator", first suggested by Darwin, explains plant nutations as endogenous movements; According to the "gravitropic overshoot" theory, nutations in plant shoots might result from delayed gravitropic responses, in the search for the upright pose; this theory was supported theoretically by the existence of an Hopf bifurcation in the so-called sunflower equation; Following experiments in space that showed the persistence of nutations without gravity, some researchers proposed a "two-oscillator" model, accounting for two mechanisms (endogenous oscillations and an exogenous feedback oscillator of gravitropic, proprioceptive or other nature).
After revision: The possible theories for plat nutations Over the last century, studies on plant nutations gave rise to three main theories about their origin: The theory of the "internal oscillator", first suggested by Darwin, explains plant nutations as endogenous movements; According to the "gravitropic overshoot" theory, nutations in plant shoots might result from delayed gravitropic responses, in the search for the upright pose; this theory was supported theoretically by the existence of an Hopf bifurcation in the so-called sunflower equation; Following experiments in space that showed the persistence of nutations without gravity, some researchers proposed a "two-oscillator" model, accounting for two mechanisms (endogenous oscillations and an exogenous feedback oscillator of gravitropic, proprioceptive or other nature).