Touch-Me-Nots

Was walking along a big patch of grassland under the freaking hot sun when I started noticing the grasses. And then I saw Mimosa..the abundance of Mimosa. Notice the darker coloured ones amongst the lighter coloured ones? Mimosa they are. The 'touch-me-nots'..Han Siu Cao (Shy Grass).

A sensitive plant, the compound leaves fold inward and droop when touched, re-opening within minutes. In abundance but yet insignificant to us most of the time. These little plants have their own unique way of ensuring their own survival. No matter how minute a life is, it will fight for its own survival till its very last moment.

Mimosa pudica

Pic I took along the road leading into Tanah Merah Kechil Avenue

The leaves fold down when stimulated or touched is as a defense mechanism, to protect itself from predators. As the fronds close, the sharp thorns are exposed to discourage animals from eating them. It also closes in response to strong rain and wind.

Some facts:

The leaves close via a physiological mechanism known as Seismonasty. This is a rapid response that occurs within a second or two. This stimulus is transmitted to other parts of the plant.

Transmission:

1) Electrical potential: The membrane is depolarized and generates an action potential which is similar to that in an animal nerve cell, only slower. It travels from cell to cell at the rate of about 2 cm/s. It may travel via the phloem.

2) Chemical factor: Released to move from one leaflet to another. The substance passes through the vascular system.

Ricca’s Factor - substance isolated that induced response in other leaves.

Turgorins, gallic acid derivatives - Hormones that give rise to action potentials.

The action potential/chemical factor would stimulate rapid unloading of potassium into the apoplast and the leaves fold.

Nice flowers of Mimosa