Mimosa - sensitive plant
I've always been intrigued by this variety of plant, because of the unusual behavior it demonstrates. Generally we expect plants to be very slow-growing, and not to exhibit any spontaneous motion. We know some sunflowers can turn their "faces" towards the sun. Some blooms (e.g. poppies, water lillies) are open during the day but close at night. Some are the other way around, blooming at night and closing during the day (datura or moonflower, evening primrose). But the motion associated with these activities is very slow and gradual (a time-lapse video can be astonishing!). The fastest-growing plant, a variety of bamboo, can grow vertically as much as 35" per day - about 1/4" every 10 minutes, almost fast enough to be visible to the naked eye! But this plant, the Mimosa pudica or "sensitive plant," will rapidly fold its compound, fern-like leaves inward and droop when touched or disturbed. The "purpose" is presumably to protect from harm - ...