Plants enrich our lives in many ways, and we often think of them as sessile organisms, confined permanently to their growing site. However, plants do move at different scales and speeds. Some of the best-known rapid plant movements are opening and closing of the stomata on the leaf surface and the quick closure of Venus flytrap (Dionaea muscipula) leaves and leaflets of mimosa (Mimosa pudicula) in response to mechanical stimulation; in contrast, a phototropic solar tracking in sunflower or reorientation of tree trunks in response to gravity are examples of slower plant motions (1). The ability of plants to disperse seeds away from the parent plant is another way plants move and colonize new habitats. It turns out that copper is involved in this ability to "move” in Cardamine hirsuta, also known as popping cress, an invasive weed species from the Brassica-ceae family (2).
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