Autumn leaves may form symmetrically to keep their tree fed as they fall

Embargoed until: Publicly released: 2025-05-07 09:01

International

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Leaves that fall every year during autumn often have a symmetrical shape, and international researchers say this may be to help keep their nutrients close to home. The researchers tested how symmetrical and asymmetrical leaves made of paper fell in a series of experiments, and they say asymmetrically shaped leaves fell about 15% slower than symmetrical shapes commonly found in nature. The researchers say when leaves fall fast, they're less likely to be caught by the wind and will therefore drop at their own tree, feeding their nutrients back to the tree through the soil.

Media release

From: The Royal Society

Leaving it all on the forest floor – Deciduous leaves may have evolved to be symmetrical and subtly lobed so they fall quicker and land near their parent tree, recycling their annually sequestered carbon. Using laser-cut paper leaves and an autumn-approximating apparatus, researchers found asymmetrical leaves fell ~15% slower than conventional symmetrical forms. As climate change has been shown to impact tree leaf shape, this could further impact forest nutrient cycling, the authors warn. Video included. Interface

Settling aerodynamics is a driver of symmetry in deciduous tree leaves
Journal of the Royal Society Interface
The apple doesn’t fall far from the tree, but what about a leaf? Our research reveals that settling aerodynamics may influence deciduous leaf shape. Rapid sedimentation promotes nutrient cycling through the soil, and symmetric leaves are fast settlers.

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Falling leaves

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Research The Royal Society, Web page The URL will go live after the embargo ends

Journal/
conference: Royal Society Interface

Research:Paper

Organisation/s: Technical University of Denmark

Funder: This work is supported by research grants from VIL‑LUM FONDEN (37475) and the Independent Research Fund Denmark (9064‑00069B).

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