image: When maple seeds become airborne, they pick up downward speed and start to spin around their center of gravity, which is located in the nut. This spinning motion is induced by the airflow around the seed as it descends to the ground. Because the spinning, helicopter-like motion of the maple seeds arises automatically it is called autorotation. The autorotation slows down the descent of the seed such that the seed can be carried further away from the tree by wind. This image accompanied the report "Leading-Edge Vortices Elevate Lift of Autorotating Plant Seeds," by D. Lentink et al. appearing in the June 12, 2009 issue of Science. view more
Credit: Photo courtesy of David Lentink