Exquisite fossils unearthed in Inner Mongolia reveal how peas got their hard coat

[Judi Lynn]

By Elizabeth PennisiMay. 26, 2021 , 11:30 AM

From roses to dogwoods to rice, flowering plants are among the most diverse and successful organisms on the planet. More than 350,000 species strong, they’re beautiful, nourishing, and critical for their ecosystems. Yet how they evolved has befuddled evolutionary biologists since Charles Darwin. Now, thanks to cutting-edge technology and a chance find in the Inner Mongolian countryside, researchers have taken a big step toward understanding how flowering plants, or angiosperms, came to be.

“It’s like a mystery being solved on CSI,” says Douglas Soltis, a plant evolutionary biologist at the University of Florida who was not involved with the work. Tracing how the traits of these ancient plants led to the structures of flowers today, he says, is “pretty exciting.”

Angiosperms evolved about 125 million years ago and now dominate many of Earth’s landscapes. They reproduce via seeds, as do the evolutionarily older gymnosperms, which include pine trees, ginkgoes, and others. But angiosperms evolved some key innovations for seed production that likely enabled their success. Their seeds form in the carpel, a tubular structure that sticks up from the center of a flower and matures into a pod that holds seeds—peas or beans, for example—inside.

The carpel grabs the pollen and transfers it to a chamber called an ovary, where seeds develop. Angiosperm seeds are encased in an inner and outer layer; the outer layer helps form the hard coat of a pea or the colored surface of a bean, for example.

More:
https://www.sciencemag.org/news/2021/05/exquisite-fossils-unearthed-inner-mongolia-reveal-how-peas-got-their-hard-coat