Alasemenia tria, a new species of Late Devonian three-winged seed

NEWS - Ovules or winged seeds are widespread and essential for wind-borne dispersal. However, the earliest ovules in the Famennian of the Late Devonian are rarely known for their dispersal syndrome and are usually surrounded by a cupule. Researchers report a new species from the Xinhang fossils.

A new taxon of Famennian ovules, Alasemenia tria, has three integumentary wings on each ovule. The prominent wings extend outward, fold inward along the abaxial side and enclose most of the nucellus. The ovules arise from the terminals on smooth dichotomous branches and lack a cupule.

This species shows that the earliest ovule integument without a cupule has an evolutionary function related to photosynthetic nutrition and wind dispersal. Seed wings appeared earlier than other wind dispersal mechanisms such as hairs, pappus, three- or four-winged seeds and fewer winged seeds.

Deming Wang from Peking University and his team conducted a mathematical analysis showing that three-winged seeds are more adaptive for wind dispersal than seeds with one, two or four wings under the same conditions. A. tria terminates leafless branches, has three wings and no cupula.

In addition to the protective and pollination functions, Alasemenia shows the nutritional and anemophilic photosynthetic functions of early ovules indicating the diversity of Famennian winged ovules and the evolutionary sequence of ovule wings. The three wings extending outward give anemochory an advantage over the four wings of Warsteinia and Guazia. Three-winged ovules are more efficiently carried by the wind.

Original research

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 13: RP92962 DOI:10.7554/eLife.92962.2

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