Eocene Green River Winged Seed
Winged Seed cf. Acer lesquereuxii
Green River Formation
Parachute Creek Member
Middle Eocene
Uintah County, Utah
This is a superbly preserved winged seed probably from Acer lesquereuxii. This specimen has remarkable detail both in the nutlet and wing.

Acer is a genus of trees or shrubs commonly known as maple. There are approximately 128 species, most of which are native to Asia, with a number also appearing in Europe, northern Africa, and North America. Only one species, Acer laurinum, extends to the Southern Hemisphere. The type species of the genus is the sycamore maple, Acer pseudoplatanus, the most common maple species in Europe.
The distinctive fruits are called samaras, maple keys, helicopters, whirlybirds or polynoses. These seeds occur in distinctive pairs each containing one seed enclosed in a nutlet attached to a flattened wing of fibrous, papery tissue. They are shaped to spin as they fall and to carry the seeds a considerable distance on the wind. People often call them helicopters due to the way that they spin as they fall.