Plants detect gravity by going with the (granular) flow

Plants need to know the direction of gravitational pull in order to grow their roots downward and their stems upward. This information is crucial whether the plant grows in your garden, on a cliffside, or even on the International Space Station [1]. While it’s been said that it took a falling apple for Newton to figure out how gravity works, our photosynthetic friends use a more intricate microscale sensor to detect gravity. This sensor consists of starchy granules called statoliths which can be found on the bottom of specialized cells called statocytes.