When “helicopters” drift down from trees, they are actually winged seeds, scientifically known as samaras. These remarkable structures are a plant’s ingenious method for seed dispersal, allowing them to travel away from the parent tree. The unique design of these seeds enables them to spin as they fall, giving them their common name and facilitating their journey to new locations.
Maple Trees and Their Samaras
Maple trees (genus Acer) are the most recognized producers of these “helicopter” seeds. Maple samaras are distinctive, typically forming in pairs with fused seed pods and spreading wings. Their size, color, and the angle at which the wings connect can vary among different maple species.
For example, red maple (Acer rubrum) samaras often have reddish wings about one inch long, joined at a 60-degree angle. Sugar maple (Acer saccharum) samaras are slightly larger, around 1.25 inches, and greener, attaching at a similar angle. Silver maple (Acer saccharinum) samaras are considerably larger, reaching about two inches long, and connect at a wider 90-degree angle.
Other Trees with Winged Seeds
While maples are well-known for their samaras, other tree species also produce winged seeds, though their appearance can differ significantly. Ash trees (Fraxinus species) produce single-winged samaras, often described as resembling a small canoe paddle.
Elm trees (Ulmus species) feature samaras that are circular or egg-shaped, with the seed located in the center of a papery disc. These flat, papery fruits appear in early spring. The tree of heaven (Ailanthus altissima) produces twisted samaras that are single-seeded and can be one to two inches long.
The Ingenious Design of Samaras
The “flight” of samaras relies on a principle called autorotation. As the winged seed falls, its specific shape causes it to spin. This spinning motion generates aerodynamic lift, significantly slowing its descent.
This lift is partly due to the formation of a leading-edge vortex, a miniature, tornado-like air current that sits atop the wing and helps create a low-pressure zone, enhancing lift. The slow, spinning fall allows the samara to stay airborne longer, increasing the chance it will be carried further by wind currents. This dispersal mechanism is an evolutionary advantage, helping seeds travel greater distances from the parent plant, thereby reducing competition for resources and increasing the likelihood of finding suitable conditions to grow. Maple samaras, for instance, can travel as far as 330 feet, or about 100 meters, from their origin.