Colloquially called propeller seeds, "whirlybirds" or "helicopters," trees that produce seeds called samaras scatter them in the wind to spiral to the ground. The samara is a dry seed with a papery wing or keel on it.
Maple trees (Acer spp.) produce samaras that spiral quickly as they drop to the ground. Other trees that produce samaras, but may not spin as ferociously as the maple's, include ash trees (Fraxinus spp.) trees-of-heaven (Ailanthus spp.) and elms (Ulmus spp.).
Other trees that don't produce samara seeds may still have modified leaves that act to catch wind and spin the attached seed as it sails to the ground. Linden or basswood trees (Tilia spp.) produce a tiny nut on a stem that has a wing-like bract. Pride-of-Bolivia (Tipuana tipu) seeds bear a pointed wing, too.
One group of tropical trees is known as the whirling nuts or whirly tree burls (Gyrocarpus spp.). The seed nut is carried by three to five wings and looks and spins exactly like a tiny helicopter to the ground.
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