Category Flowers

Many of us may have heard of or even seen or touched the touch-me-not plant also called the sensitive plant. The moment we touch it the plant quickly folds its leaves inward. It unfolds the leaves when it feels safe enough. The plants have different types of cells that help them fold in response to external stimuli (such as touch, heat light etc.), and unfold.

Scientifically known as Mimosa pudica, the touch-me-not plant spends a lot of energy not during this folding unfolding act. It loses a chance to photosynthesise too. And yet it continues to do this because scientists believe this behavior could have evolves as a response to guard itself against predators, especially herbivores. Closed or closing leaves are assumed to have several benefits. They could make it tougher for animals to detach the leaves from the stems the animals could be fooled into believing the plant is dying or dead and is of no use and the sudden closure of the leaves could shake off insects or even startle herbivores into moving away from the plant while all these are interesting by themselves, something even more fascinating came about in a 2014 study.

A group of researchers decided to study if plants could be “trained” to change their behaviour, and used touch-me-nots for the study. From a height of about 15 cm. test plants in pots were dropped onto foam. This was repeated, and after a point, the plants no longer folded their leaves, perhaps since they did not sense any harm. Intriguingly, even a month after this experiment, the plants remembered to not fold their leaves when the experiment was taken up again Scientists concluded that plants could “learn”, a trait usually attributed to animals. And this learning could mean that by not folding their leaves the touch-me-nots could save energy.

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The lifecycle of plants differs from species to species. There are those that complete their lifecycle in one year (called annuals) and those that live for more than one year, flowering once or many times in their lifetime (perennials)

Those that flower only once, produce seeds and die. The next generation of the plant is established from these seeds and the cycle gets repeated. Such plants are known as monocarpic. (Whereas polycarpic plants are those that flower many times during their lifetime.) Kurinji is monocarpic. Monocarpic plants flower only on attaining maturity. The time taken to mature varies for different species of kurinji. So, different species of kurinji have different intervals of flowering too.

Neelakurinji matures in 12 years time and flowers every 12 years. That is, it takes another 12 years for the seeds to sprout and grow 30 to 60 centimetres high for another glorious bloom. Each shrub reproduces once in its lifetime and dies after flowering.

India is home to nearly 46 species of kurinji, with most of them showing an unusual flowering behaviour, varying from annual to 16-year blooming cycles.

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Flowers get their scent from a mixture of volatile organic compounds (VOCs) produced by the plant. The fragrance is often strongest in the petals.

Different flowering plant species encompass a diversity of VOCs and no two fragrances are the same. The purpose of scent is to attract pollinators and repel herbivores. Flowers also use colour and shape to attract pollinators. The scent is strongest when a flower is ready for pollination – a full bloom’s smell is powerful than a bud’s.

Maximal emissions also coincide with the active phase of visiting pollinators. Plants pollinated by moths usually emit the most fragrance in the evening or night (when moths are active), while plants pollinated by bees produce the most scent during the day (when bees are active).

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