The sight of spinning objects descending from trees often sparks curiosity, especially when they twirl gracefully to the ground like miniature helicopters. Their unique descent captures attention. Children and adults alike often pick them up, marveling at their design before tossing them into the air to watch their playful spin once more. This common phenomenon is a widespread part of many seasonal landscapes, particularly during autumn.
The Maple Tree Connection
The most familiar source of these spinning seeds is the maple tree. Maples produce samaras, a type of dry fruit with a flattened, wing-like structure. These samaras appear in paired formations, resembling a small “V,” though they often break apart into single units before or during their fall.
Common maple varieties known for their production of these winged seeds include the red maple, silver maple, Norway maple, and Japanese maple. Red maple samaras, for instance, are reddish and about an inch long, connecting at a 60-degree angle. Silver maples produce larger samaras, approximately two inches long, joined at a 90-degree angle. When mature, these winged seeds detach from the tree.
How Helicopter Seeds Fly
A maple samara’s design allows it to spin like a helicopter blade as it falls, a process called autorotation. This spinning motion is an aerodynamic mechanism. As the samara descends, its single wing interacts with the air to create lift and drag, slowing its fall significantly.
As the samara spins, it generates a tornado-like vortex along its leading edge. This leading-edge vortex reduces air pressure above the seed’s upper surface, pulling the wing upward and doubling the lift compared to a non-spinning seed. This aerodynamic trick, similar to how insects or hummingbirds hover, allows the seed to drift much farther from the parent tree. This increased dispersal distance is an evolutionary advantage, helping the species spread and reducing competition for resources near the parent plant.
Other Trees with Winged Seeds
While maples are the most widely recognized for their “helicopter seeds,” other tree species also produce winged seeds, though their forms and flight characteristics may differ. These winged structures enable wind dispersal.
Ash trees, for example, produce samaras with a single, elongated wing, often hanging in clusters. These seeds, sometimes called “keys,” are paddle-shaped and can be 1 to 2 inches long. Elm trees produce samaras where the seed is centrally located within a nearly round, papery circle. These flattened, wafer-like seeds float on the wind. The Tree of Heaven, an invasive species, also produces winged seeds, but its samaras are somewhat twisted with the single seed in the center, appearing in large clusters.