Sensitive plant

The plant that moves at a touch

The sensitive plant (Mimosa pudica) is a small creeping plant of the pea family Fabaceae, 10–40 cm tall, famous for a rare ability: when touched, shaken or blown on, it quickly folds its leaflets together and lowers its stalks, as if it were "shy". This very rapid movement, called thigmonasty, is one of the best-known forms of fast movement in the plant world; after a few minutes the leaves reopen. Its flowers are charming pink-lilac pompoms, small and globe-shaped.

Origin and habitat

It is native to the tropical regions of Central and South America but has become naturalised across much of the warm world, including Africa and Asia, where it often grows as a weed in disturbed ground.

Cultivation and care

It is easily grown as a curiosity, often in a pot and as an annual. It wants plenty of light or full sun, well-draining soil kept moist, and warm temperatures: it dislikes cold and cannot tolerate frost. It flowers in summer. In winter, in temperate climates, it should be kept sheltered in a bright, heated spot.

Did you know?

Besides its movement at a touch, the sensitive plant also makes "sleep" movements (nyctinasty): it closes its leaves in the dark and reopens them in light. The sudden folding probably serves to startle herbivorous insects or reduce exposure, as a defence against predators.

Conservation

It is not a threatened species; indeed, in many tropical regions it is considered a weed. Its worldwide spread is due precisely to the ease with which it adapts and reproduces.