Illustration by Matteo Giuseppe Pani

Our thanks to Asher Elbein, writing in The Atlantic, for this:

The Secret of Plant ‘Sight’

Scientists have discovered that a mysterious behavior might come down to air.

On a shelf lined with terra-cotta pots, herbs bend their stems toward the nearest window. In a field of golden wildflowers, leaves rotate with the path of the sun. In a dappled forest, vines twine up trees, reaching ever upward and away from the dark.

Since ancient times, plants’ ability to orient their eyeless bodies toward the nearest, brightest source of light—known today as phototropism—has fascinated scholars and generated countless scientific and philosophical debates. And over the past 150 years, botanists have successfully unraveled many of the key molecular pathways that underpin how plants sense light and act on that information.

Yet a crucial mystery has endured. Animals use eyes—complex organs of lenses and photoreceptors—to gain a detailed picture of the world around them, including the direction of light. Plants, biologists have established, possess a powerful suite of molecular tools for measuring illumination. But in the absence of obvious physical sensing organs such as lenses, how do plants work out the precise direction from which light is coming?

Now a team of European researchers has hit upon an answer. In a paper published recently in Science, they report that a roadside weed—Arabidopsis, a favorite of plant geneticists—uses the air spaces between its cells to scatter light, modifying the path of light passing through its tissues. In this way, the air channels create a light gradient that helps seedlings accurately determine where light is coming from…

Read the whole article here.