Dandelion seeds typically fall within seven feet of their parent. On a windy, warm, and dry day, those seeds can soar 20 miles with some reaching up to 95 miles away from the parent. Think of how the bristles off of a dandelion blow off when making a wish. How is it possible for a dandelion seed to float through the air with such effectiveness? Scientists decided to figure this out and came up with some fascinating conclusions.
Flight of the pappus
Dandelion seeds gain their aerodynamics from a set of bristles called pappus. The dynamics of the pappus have confused scientists for years. The University of Edinburgh’s Dr. Naomi Nakayama utilized advanced photography to capture the pappus in action.
Dr. Nakayama constructed a vertical wind tunnel and put some dandelion seeds inside. She allowed some seeds to float in the wind while others remained tethered. After reviewing the photographs, Nakayama and her team made the interesting discovery.
How pappus work
Many large seeds travel through the air using wings. The tiny bristles are so effective because of their small size. If the bristles grew any larger, the dandelion’s ability to float through the air would be severely limited. The advanced photography revealed some clear answers as to why.
Scientists revealed a vortex ring, or air bubble, surrounding the pappus in a perfectly calibrated fixed distance. Each bristle works together to obstruct airflow through the pappus. Picture an invisible disk surrounding the dandelion. However, the separate vortex ring allows for four times the drag per unit area of a disk. This acts as a small-scale parachute.
Pappus in nature
These small bristles are not specific to dandelions. Nakayama pointed out that other tiny plant and animal species, such as Guinea Fowls, use the same method.
Scientists should be able to apply this aerodynamic technology on a smaller scale.