The poet William Wordsworth once wrote of daffodils “dancing in the breeze,” and Shakespeare before him described “daffodils that… take the winds of March with beauty.” Biomechanists have determined that daffodils dance by design. In a paper entitled “Reorientation of Daffodil Flowers in Wind: Drag Reduction and Torsional Flexibility,” researchers concluded that daffodils turn their backs to the wind to reduce drag (Etnier and Vogel, 2000). They can do that thanks to their stems’ ability to twist and bend.
Daffodil stems are lenticular, or lemon shaped, in cross section, which helps the flowers turn away from the wind.
Daffodils carry their flowers at an angle of 60–90 degrees to the stem. This arrangement makes them vulnerable to damage if a strong gust hits them head on. But daffodils have a strategy for dealing with this problem. First, thanks to the material properties and lenticular shape of their stems, they are able to rotate away from the wind and lower their profile by bending. Second, daffodil flowers have the ability to reduce drag when their backs are turned to the wind. As wind intensity increases, the petals are blown around the cup, giving the flowers a streamlined shape.
When hit by a strong gust of wind, daffodils reduce drag by twisting and bending, and their petals form a cone.
To study how daffodils respond to wind, the researchers placed daffodils in a wind tunnel. As wind velocity was increased, the flowers began to turn and the stems began to bend, until at speeds in excess of 30 mph, the flowers were turned a full 180 degrees from the wind, the tips of the petals were pointing downwind to form a cone and the stems were bent almost parallel to the wind direction (see the illustration below). When the wind tunnel was turned off, the stems stood back up and the flowers turned back around and assumed their normal shape, as though nothing had happened.
Outdoors on a breezy day, this back and forth can occur over and over, with each strong gust. And the daffodils, which look elegant and dignified when the weather is calm, appear to shimmy and dance to the music of the wind.
For the original article, point your web browser to the American Journal of Botany and then enter “daffodil” into the search field. For a nice explanation of the article in layman’s terms, see a piece by Adam Summers of the University of Washington here.
