Wet Plants Feel the Burn
A study in the journal New Phytologist confirms the gardener's belief that droplets of water resting on some types of leaves can focus sunlight until the plant's surface actually burns. Karen Hopkin reports
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If you’ve ever had a garden or grown flowers in a window box, you’ve probably heard that you shouldn’t water your plants at high noon because their leaves might scorch. Now a study in a journal called New Phytologist confirms that water droplets can focus sunlight to the point that it burns, a finding that applies to plants and to people.
Check any gardening blog and the question of whether water can burn comes up with some regularity. But the problem had never been thoroughly tested. So scientists at Eotvos University in Budapest decided to do just that. And they found that the results depend on how hairy you are.
On leaves that are really smooth, like those from a maple tree, water doesn’t do much damage. But leaves that have tons of tiny hairs, like a fern, can hold spherical water droplets in focus above a leaf’s surface. Those drops act like mini magnifying glasses, focusing the sunbeams on an area that will subsequently fry.
And the same is true on you. Cooling off in the pool might seem like a stellar idea. But the resulting water droplets, propped up by your body hair, poolside, could turn you from lounger to lobster.
—Karen Hopkin
[The above text is an exact transcript of this podcast.]
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