How does the eastern cottonwood "sing"?

Hello, I’m Amanda McNulty with Clemson Extension and Making It Grow. In the 1957 movie Tammy and the Bachelor, Debbie Reynolds sings the song, "Tammy," nominated as Best Song, which has this line “I hear the cottonwoods whispering above.” Well, the leaves on eastern cottonwoods, Populus deltoides, actually are known for making what one person describes as "the lullaby of the prairies." The leaves are about five inches long, with toothed edges and extended tip. Their petiole is what lets them "sing," so to speak. Most leaves have rounded petioles that give them stability, but on cottonwoods, the petioles are very long, as long as the leaves, and are flat and slender. The slightest breeze sets off this huge rustling sound. Look it up on the internet and listen to some of the recordings – it is LOUD.