“It’s exceptional to launch it with this spiral,” said Dwight Whitaker , a physics professor at Pomona College in California who was not involved with the witch hazel research but who has studied how a different plant, the hairyflower wild petunia, catapults its seeds into the wild. “It’s just really cool how they’ve documented how it does it.”

What the researchers don’t quite understand is how seeds from different fruits on the same witch hazel plant can spin in different directions, as if a quarterback sometimes throws right-handed half of the time and left-handed half of the time.

In addition to using high-speed cameras, the researchers also put the plants inside magnetic resonance imaging machines so that they could examine the hidden structures within the plant and the fruit without having to cut it apart.

“We do not need to use any radiation or sample preparation which could be damaging to the sample,” said Linnea Hesse , a postdoctoral researcher who performed the M.R.I. scans. “We can basically perform repetitive imaging on the same plant as it grows over time.”

The same M.R.I. techniques could be used to study the movements of other plants such as how the Venus fly trap catches and eats bugs.

The German researchers want to study in more detail how the witch hazel launches its seeds, in particular how it is applying a torque to make it spin. They imagine that perhaps it could inspire engineers to design a new kind of sensor that detects when the humidity is low and then opens a valve in response.