“Helicopter seeds” are winged seeds that twirl as they fall from trees. Botanically known as samaras, these dry fruits have a flattened, papery wing that develops from the ovary wall. Their spinning motion aids in seed dispersal, allowing them to travel farther from the parent tree and increasing germination chances.
Maple Trees and Their Seeds
Maple trees (Acer) are the most well-known producers of “helicopter seeds.” Each maple samara typically consists of two conjoined wings, each encompassing a single seed. This double-winged, V-shaped structure is characteristic of maples, distinguishing them from other trees that also produce samaras.
Many common maple species produce abundant samaras. Red maples (Acer rubrum) produce large quantities of seeds with reddish wings about one inch long. Silver maples (Acer saccharinum) also produce numerous samaras, which are larger, around two inches long, and typically connected at a 90-degree angle. Norway maples (Acer platanoides) produce seeds with a broader angle between the wings, while Japanese maples (Acer palmatum) feature smaller, often reddish, winged nuts. Samaras mature and are released from late spring through autumn, depending on the species.
The Mechanics of Flight
The “helicopter” nickname stems from their flight mechanics, a process known as autorotation. As a samara detaches from the tree, its asymmetrical design and weight distribution cause it to spin horizontally, much like a miniature propeller.
This spinning motion creates a stable leading-edge vortex, a tornado-like air current that sits on top of the wing. This vortex reduces air pressure above the wing, producing additional lift and increasing drag. The combination of lift and drag extends the seed’s time in the air, allowing even light breezes to carry it considerable distances, sometimes over 100 meters. This efficient wind dispersal mechanism helps the seeds spread away from the parent tree, reducing competition for resources like sunlight and water.
Other Trees with Samara Seeds
While maples are the most prominent, other tree species also produce samara seeds, though their appearance and flight characteristics may differ. Ash trees, belonging to the genus Fraxinus, produce samaras that are single-winged. These seeds, sometimes called “keys,” have one elongated wing, resembling a small paddle, and often hang in clusters. Ash samaras are designed for wind dispersal but lack the dual-winged, spinning flight of maple seeds.
Elm trees, of the genus Ulmus, also produce samaras, but their seeds are typically located in the center of a circular, papery wing. These wafer-like seeds are often light green when young and become dry and brown as they mature. Elm samaras are lightweight and are also dispersed by wind, often appearing before the leaves emerge in spring. Sycamore trees (Platanus genus) are another example; while some sycamore maples produce V-shaped samaras, true sycamore trees have seeds contained within large, fuzzy balls that disperse differently.