1. Rapid leaf folding: When the plant is touched or disturbed, its leaflets rapidly fold inward and the entire leaf droops. This folding movement occurs due to changes in turgor pressure within specialized cells called pulvini at the base of the leaflets. By quickly wilting, the plant may appear less appetizing or even mimic wilted or diseased vegetation, deterring potential herbivores.
2. Leaf closure and stem drooping: In addition to leaflet folding, the sensitive plant may exhibit leaf closure and stem drooping. The petioles (leaf stalks) collapse, and the entire leaf droops downward. This may further enhance the plant's camouflage and defense by reducing its exposure and vulnerability to predators or grazing animals.
3. Chemical defense: Mimosa pudica produces a variety of chemical compounds, including tannins, alkaloids, and saponins, which can serve as deterrents to herbivores or pathogens. These compounds may render the plant unpalatable or even toxic to potential predators.
4. Mimicry: Some researchers suggest that the rapid folding of the leaves and the drooping of the entire plant may serve as a form of mimicry. By mimicking fallen or damaged leaves or simulating disease, the plant may deceive potential herbivores and avoid consumption.
It is important to note that while these defense mechanisms can provide some degree of protection, they may not be entirely foolproof. If the threat or disturbance persists or is severe enough, the plant's defenses may be overcome. Therefore, Mimosa pudica relies on a combination of physical and chemical defenses to increase its chances of survival.