Facing the Wind – Daffodil Style

030430If you watch a daffodil in the wind you will notice its head down and its face turned away from the wind.  The daffodil’s ability to turn its back to the wind is found in the unique shape of its stem.  The lemon-shaped cross section of a daffodil stem enables it to twist away from the wind rather than bend and break like the more vulnerable tulip stem.

Most of us recognize that a garden hose with a circular cross section bends more easily than it twists, but a plastic coffee stirrer twists more easily than it bends.

Tulips whose blossoms turn skyward rather than facing down have a circular cross-section.  The stem behaves like a garden hose with little resistance to bending.  The twistiness of the daffodil, which behaves more like a plastic coffee stirrer, is fourteen times greater than its bendiness.  This explains why it’s far more likely to turn in the wind than bend over.

Wind tunnel experiments show that the force on the daffodil flower is lowest when it is rotated a hundred and eighty degrees from the wind direction.  At wind speeds of thirty kilometres per hour the stem begins to bend over in addition to twisting, bringing the flower closer to the ground, where the wind speed is lower.  Even in winds of sixty kilometres per hour the petals survive by consolidating themselves into tight bundles.

So next time you’re out in the wind, why not try to cope by bending and twisting like the daffodil!