An intriguing discovery 360 million years old. In China, a fossilized seed reveals an unsuspected plant past. What secrets does this unique seed hold?
Scientists have studied this winged fossil seed,
Alasemenia, discovered in a Chinese mine. Using mathematical modeling tools, they reconstructed its dispersal mechanism, similar to that of modern seeds.
Unlike other seeds from the Late Devonian,
Alasemenia lacked a protective cupule. Moreover, it had three wings that were perfectly adapted for wind dispersal, a major innovation for this period. Researchers' analysis revealed that three wings offer good stability, ensuring effective rotation and optimal movement.
This stability would have allowed
Alasemenia to travel long distances. A definite evolutionary advantage for these plants seeking to colonize new territories.
Deming Wang, professor of geology, emphasizes that this seed could be the ancestor of modern plant wind dispersal systems. A key adaptation in plant history.
Reconstruction.
(a) Alasemenia tria with three wings extending outward.
(b) Alasemenia tria with one of the three wings partially removed to show the nucellar tip.
(c) Guazia dongzhiensis with four wings extending inward (Wang et al., 2022).
Scale bars, 5 mm (0.2 in).
These discoveries help us better understand how plants developed sophisticated wind dispersal strategies. A natural feat that has shaped terrestrial ecosystems. The complete study was published in
eLife.
What is wind dispersal in plants?
Wind dispersal, or anemochory, is a natural strategy used by some plants to spread their seeds over long distances. This allows them to avoid competition with the parent plant for resources like sunlight or nutrients and increases their chances of colonizing new territories.
Plants employ various adaptations to promote seed dispersal. Some, like maples, produce seeds with wings called samaras, which spin through the air like helicopters to maximize their range. Others, like dandelions, develop parachute-like structures that help them take flight with the slightest breeze.
In the earliest land plants, these mechanisms were rare. However, the discovery of a 360-million-year-old fossil seed,
Alasemenia, shows that some plants had already begun developing specialized structures, marking an important step in the evolution of seed plants and the history of plant biodiversity.
Author of the article: Cédric DEPOND