Scientists have discovered that plants can carry out difficult arithmetic calculations to prevent them from starving.

To survive in the absence of sunlight, plants perform division equations during the night in order to ration stores of starch until the dawn, when the sun rises.

By counting their starch and dividing it by the number of hours left until morning, the plants can make sure they have enough nutrition to last the night.

Plants' survival depends on starch, which is produced from carbon dioxide and sunlight during the day to provide energy during the night.

If the plants were to run out of starch, they would begin to starve and stop growing.

The discovery is the first known example in nature of sophisticated arithmetic carried out in plants.

"The capacity to perform arithmetic calculation is vital for plant growth and productivity," Professor Alison Smith, a metabolic biologist who helped make the discovery, told the Telegraph.

"The calculations are precise so that plants prevent starvation but also make the most efficient use of their food. If the starch store is used too fast, plants will starve and stop growing during the night. If the store is used too slowly, some of it will be wasted."

Researchers from the John Innes Centre in Norwich discovered the hidden ability after studying Arabidopsis, a small flowering plant in the mustard family.

They found that the plants used their starch at a steady rate throughout the night, so that about 95% of their stock had been used up by dawn each day.

Plants are also capable of sending sophisticated communications to each other. Chemical messages exchanged between plants allow them to send out alerts when under attack by pests.

"Plants not only respond to reliable cues in their environments but also produce cues that communicate with other plants and with other organisms," said Richard Karban of the University of California, who co-authored the study on plant behaviour.

Even stranger, women gardeners' voices speed up growth of tomato plants much more than men's, according to a Royal Horticultural Study.

In an experiment run over a month, the RHS research found that tomato plants grew up to two inches taller if they were read to by a female rather than a male. In fact, some plants actually grew less when read to by a man, than if they were left completely alone.