First Flower on Earth: Scientists Discover Structure And Shape of the Earliest Flowers

Scientists reveal what the first flower may have looked like
The ancestral flower was bisexual, with multiple whorls (concentric cycles) of petal-like organs in sets of threes. Photo released on August 1. Hervé Sauquet/Jürg Schönenberger

Once upon a time on Earth, there was a first flower.

Nature provides plenty of cues to help us imagine what the planet looked like 250 million years ago. But we lack concrete evidence in order to conjure the details of the very first instances of various forms of life: the first tree, the first nut, the first egg. Considering how important flowers are to plant life, botanists are frustrated by the lack of information about their evolution. Now, scientists have given a glimpse of what the original flower looked like, moving one step closer toward solving one of the greatest botanical mysteries

Flowering plants, also called angiosperms, originated at least 140 million years ago. The oldest flower fossils documented, however, are about 130 million years old. That gap in time raises many questions about what the ancestors of those fossils looked like.

Angiosperms account for about 90 percent of the plant kingdom and include more than 250,000 different species. The diversity of their reproductive structure—that is, the flower—is vast: shape, size and color vary widely, as do their geographic location: A pink chrysanthemum, for example, looks so different from the vibrant green-leaf hosta. Such variety makes narrowing it down to one specific image of the first flowering plant particularly tricky.

Researchers banded together to find a way to use the diversity to their advantage. In a new study released in the journal Nature Communications on Tuesday, a team of biologists shared a depiction of what they believe the first flowering plant looked like: dainty and white, with curved petals arranged in threes.

Hervé Sauquet, lead author of the paper and a science collaborative he initiated called eFLOWER, created a family tree of flowering plants using a method called ancestral state reconstruction. Using descriptions of flowers dating as far back as 1783, his team collected data on various structural traits—the shape of each flower at its branching points; its sexual organs; the arrangement of each plant's petals; and many other features—for 792 different species, gathering more than 13,400 data points.

By comparing that information with genetic data on flowers spanning as far back as such information exists, the scientists developed a depiction of the likeliest structure and shape of the earliest flowers.

147023_web
The researchers also reconstructed what flowers looked like at all the key divergences in the flowering-plant evolutionary tree. Hervé Sauquet/Jürg Schönenberger

The image isn't drastically different from what flowers look like today. Like many contemporary flowers, the ancient flowering plant the researchers conceived has both female and male parts, referred to as pistils and stamens, on the same blossom. Its arrangement and upturned petals also are similar to the flowers that bloom on Earth now.

The most surprising feature of the new illustration is the arrangement of the flower's stamens, petals and protective, petal-like parts in concentric circles, or whorls, in groups of three. In contrast, today's flowers bloom in spirals. That aspect of the image is what Sauquet expects to be challenged on the most. "I think many people are not going to believe us at first," he told The Guardian recently.

The researchers' image also suggests that the ancient flower would have had three or four whorls for each organ, whereas most living flowers in modern times have fewer. According to Sauquet, the reduction of whorls in flowering plants may have evolved to provide easier access for pollinators to approach.

"To get the living flowers, it is very simple: Just get rid of some whorls," Sauquet said. Only one whorl of sepals is needed for protection, he explained, and another to attract pollinators like bees.

How that first flower may have smelled is still unknown.

First Flower on Earth: Scientists Discover Structure And Shape of the Earliest Flowers | U.S.
{{label}}
{{title}}
EDITOR'S PICK