Moon’s gravity could govern plant movement like the tides

21st Aug 2015

IT’S a drag. The movement of plant leaves may be partially governed by the gravitational pull of the moon, just like ocean tides.

Some plants’ leaves rise and fall during the day-night cycle, mostly in reaction to light in their environment. But plants grown in the dark have similar cycles, which hints that something else may be at work as well.

Peter Barlow of the University of Bristol, UK, looked at data recorded since the 1920s on the leaf movement of beans and other plants. He matched these with estimates of the gravitational influence of the moon at the time and location of these experiments.

The two data sets don’t match exactly, says Barlow, but generally, when the lunar tide turns, so do the leaves. “If you look at enough of these correlations, they all seem to be strong enough to make you believe they might be causal,” he says.

It’s not clear exactly how the moon could influence this change, but it may be associated with the movement of water in a part of the plant called the pulvinus, the “joint” where leaf meets stem.

“Scientific work on lunisolar impact on biological systems has sometimes been almost ridiculed,” says Catarina Rydin of Stockholm University in Sweden, who discovered a plant whose pollination is governed by the full moon. “Papers like this are very important.”

The paper was publised in Annals of Botany.

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