The seeds of some trees flutter through the air with aerodynamic precision. Equipped with the same method a bird uses to fly, a mini tornado above the winged seed produces a force that sucks air up from under the seed. This force is called lift. Sometimes called propellers, whirlybirds or helicopters, winged seeds are scientifically named samaras. Samaras have one to two seeds with a rigid wing. The wing has a slight pitch, causing it to spin like a propeller. Depending on the wind, samaras can travel more than a mile before landing on the ground.
The round, dense canopy of the Norway maple (Acer platanoides 'Crimson King') makes it a favorite of landscapers. Easy to transplant, the tree grows rapidly, producing a refuge of heavy shade for nearby travelers. Birds find sanctuary in its thick awning and enjoy Norway maple's double-winged samara seeds that are horizontal and not hanging.
It adapts to urban areas, tolerating both shade and drought, but has an aggressive root system that can break up sidewalks. Norway maple is winter hardy in U.S. Department of Agriculture plant hardiness zones 3B through 7B.
Tree of Heaven
Tree of heaven (_Ailanthus altissima_) produces a samara seed with a paper-like wing around it. Yellow-green flowers on female trees produce seeds in vast quantities from late summer through early fall.
When dropping, the samara seeds flutter and spin in the air. The seeds are so successful in dispersing and germinating that seedlings even grow in cracks of pavement. The tree, a native of China, survives where other trees cannot. It thrives under any conditions: hot, dry, wet or cold.
Tree of heaven features large compound leaves like a walnut tree and smooth grey bark. Trunks can grow up to 5 feet in diameter. Crushed leaves and all parts of the tree have a foul odor described as rotten peanut butter. Considered invasive in some areas, tree of heaven is difficult to kill. It's winter hardy in U.S. Department of Agriculture plant hardiness zones 5A through 8A.
Green ash (_Fraxinus pennsylvanica_) reaches 60 feet high and 45 feet wide. Although it has an irregular shape when young, green ash is symmetrically oval at maturity. Glossy deep green leaves turn yellow in fall. Female trees produce an abundance of samara seeds, which lead to a messy landscape.
Green ash adapts to a variety of growing conditions and tolerates both wet and dry sites. USDA hardiness zones 8 and 9 are perfect for green ash trees. The trees are susceptible to common borers such as Ash borer, lilac borer and carpenter worm. Keep the tree healthy, to ward off borers, by watering and fertilizing during dry weather.