Wild wheat shows its muscles

A seed drill: I The seed and part of the awn in the soil (the red arrow is pointing to a silica hair). II When humidity rises during the night, the awns become erect and push the grain into the soil, because the hairs prevent any movement out of the soil. III As the airs dries the next day, the awns bend apart again. This tensions the drill that will push the seed further into the ground during the following night. Image: Planck Institute of Colloids and Interfaces