While plants are sessile organisms, they display an extraordinary variety of movements. The interest of these is two-fold: (i) they rely on a rich diversity of physical mechanisms and (ii) they occur in many different physiological contexts, ranging from development to adaptation or even reproduction. In this seminar, I will give an overview of my past research projects on plant movements. I will briefly present works on autonomous plant motions before detailing recent projects on two examples of plant responses to a fluctuating environment. First, I will focus on the dynamic aspects of gravitropism (the ability of plants to align with the vertical). How does gravitropic response depend on previous stimuli? I will present experimental results showing several regimes of tropic response, where wheat seedlings not only sum but also subtract consecutive stimuli. Second, I will focus on the fast motion of Mimosa pudica, which folds its leaves in seconds upon being touched. We will see how kinematics and mechanical assays at the organ-scale challenge the classical scenario of a purely osmosis-driven motion. I will then discuss an alternative scenario involving intercellular spaces and present our first attempts at testing it.