Researchers have found the earliest evidence of a winged seed in the Jianchuan mine in China. This fossil is 365 million years old and dates back to the Famennian period (371 to 359 million years ago). By studying the fossil, researchers assert a new understanding of plant evolution and reproduction.
For many plants, seeds serve the core purpose of reproduction. To adapt to the changing environments, seeds have evolved into several shapes and sizes and often developed extra survival mechanisms. For instance, few seeds developed wing-like structures to glide with the force of wind. Wing-like structures can be like a parachute or like a helicopter.
The first seed is considered to have evolved in the faunal stages in the Late Devonian epoch. Fossils indicate that almost all seeds were covered with an extra protective layer called Cupule, and none of them evolved wings.
Up to now, only two groups of Famennian seeds have been discovered to grow wing-like structures – Warsteinia and Guazia. These Famennian seeds had four wings.
The lead author Deming Wang examined the seed sample collected from the Anhui province in China and placed it in the Alasemenia tria genus.
Each seed, 2.5–3.3cm long, had three wings with no cupules and is the second oldest ever found with wings. Computer simulations demonstrate that the three-winged seeds are better at dispersal by wind than the seeds with one, two, or four wings.
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These findings suggest that the seeds lacking couples evolved wing-like structures to help scatter with the wind. Researchers state that seeds with three and four wings evolved first, followed by the seeds with lesser wing numbers.
The senior author Pu Huang says, “Our discovery of Alasemenia adds to our knowledge of the origins of wind dispersal strategies in early land plants. Combined with our previous knowledge of Guazia and Warsteinia, we conclude that winged seeds as a result of integument outgrowth emerged as the first form of wind dispersal strategy during the Late Devonian, before other methods such as parachutes or plumes.”
“The three-winged seeds seen in Alasemenia during the Late Devonian would have subsequently been followed by two-winged seeds during the Carboniferous period, and then single-winged seeds during the Permian,” Wang continues.
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Journal Reference
- Deming Wang, Jiangnan Yang, Le Liu, Yi Zhou, Peng Xu, Min Qin, Pu Huang (2024) Alasemenia, the earliest ovule with three wings and without cupule, eLife. DOI: 10.7554/eLife.92962.3
