Their aim is simple: To carry a fairly heavy seed a good distance from the parent. After all, what good would it do to plant your offspring right next to your spreading, shady self where they would lack the sun and space to survive very long? The samaras wait for a good breeze, let go and can twirl through the air long enough to land far from “mom.”
Pick one up and examine its design. Each is finely formed in a way that makes it spin and hang in the air instead of plummeting to the ground. That a tree could develop such an aerodynamic technique for dispatching its seeds is yet another miracle of evolution. Joyce Kilmer may have marveled at trees, but even their tiny offspring are amazing.