The Big Bloom—How Flowering Plants Changed the World

In the summer of 1973, sunflowers sprouted in my father’s food garden. They seemed to grow overnight in a couple rows he had loaned that year to new California neighbors. I was just six years old at the time, and these gaudy plants first turned me off. Such unusual and vivid flowers were out of place amid the respectable beans, peppers, spinach, and other crops that we had usually planted. However, the sunflowers’ beauty eventually won me over. Their blazing halos broke up the monotony of green that had taken over the garden by late July. I stared at the birds that hung upside down on the hairy, gold disks, flapping their wings and plundering the seed. Sunflowers defined flowers for me that summer and altered my perception of the world.

Flowers have a way of achieving this. They started affecting the appearance of the globe practically as soon as they emerged on Earth, some 130 million years ago, during the Cretaceous epoch. That is very recent in geologic time: if all of Earth’s history were compacted into one hour, blooming plants would only exist for the past 90 seconds. However, after they took root some 100 million years ago, they quickly diversified into an explosion of variety that gave rise to the majority of the flowering plant groups seen today.

Flowering plant species now exceed ferns and cone-bearing trees, or conifers, which existed for 200 million years before the first bloom. Flowering plants feed humans and the rest of the animal kingdom with nutrients, which is essential to our survival. Walter Judd, a botanist at the University of Florida, said, “If it weren’t for flowering plants, we humans wouldn’t be here.”

From oaks and palms to wildflowers and water lilies, over kilometers of cornfields and citrus orchards to my father’s garden, blooming plants have come to dominate botany and agriculture. They also rule over an ethereal world sought by artists, poets, and ordinary people in pursuit of inspiration, consolation, or the sheer joy of admiring a flower.

“Before flowering plants appeared,” says Dale Russell, a paleontologist at North Carolina State University and the State Museum of Natural Sciences. “The world was like a Japanese garden: peaceful, somber, green; inhabited by fish, turtles, and dragonflies.” After blossoming plants, the earth resembled an English garden, full of vibrant colors and diversity, frequented by butterflies and honeybees. Flowers of all sizes and hues grew amid the vegetation.”

That rapid transition is one of the most significant events in the history of life on Earth. What caused blooming plants to overtake the world’s flora so quickly? What was their greatest innovation?

Flowering plants are referred to as angiosperms by botanists, which derives from the Greek words for “vessel” and “seed.” Angiosperms, unlike conifers, generate seeds in fruit rather than open cones. Each fruit includes one or more carpels, which are hollow chambers that protect and nurture the seeds. Carpels may be found by slicing a tomato in half. These structures are the distinguishing feature of all angiosperms and are critical to the viability of this vast plant group, which includes over 235,000 species.

When and how did the first blooming plants emerge? Charles Darwin pondered the topic, and paleobotanists are still looking for an answer. Throughout the 1990s, discoveries of fossilized flowers in Asia, Australia, Europe, and North America provided crucial evidence. At the same time, the discipline of genetics provided a whole new set of instruments for the search. As a consequence, current paleobotany has expanded at a rate comparable to the Cretaceous flower outburst.

Now, old-school fossil collectors with shovels and microscopes share notes with molecular scientists who use genetic sequencing to trace contemporary plant families back to their roots. These two sets of researchers don’t always end up at the same spot, but they both agree on why the quest is vital.

“If we have an accurate picture of the evolution of a flowering plant,” says Walter Judd, “then we can know things about its structure and function that will help us answer certain questions: What kinds of species can it be crossed with?” “What types of pollinators are effective?” This, he claims, leads to more reasonable and effective agricultural practices, as well as a better grasp of the greater evolutionary process.

Elizabeth Zimmer, a molecular scientist at the Smithsonian Institution, has been reconsidering that process in recent years. Zimmer has been researching the DNA of modern flowering plants in order to determine their evolutionary history. Her work was boosted in the late 1990s by a federally financed research called Deep Green, which was designed to promote collaboration among scientists investigating plant evolution.

Zimmer and her colleagues started searching their shared data for groupings of plants with similar hereditary features, aiming to finally uncover a common ancestor for all flowering plants. According to current research, the oldest extant lineage, dating back at least 130 million years, is Amborellaceae, which comprises just one known species, Amborella trichopoda. This little woody plant, sometimes referred to as a “living fossil,” can only be found on New Caledonia, a South Pacific island known for its primeval vegetation.

But we don’t have an Amborella from 130 million years ago, so we can only speculate if it looked similar to today’s version. We do have remains of other extinct flowering plants, the oldest of which are buried in strata 130 million years old. These fossils provide the sole physical evidence of what early flowers looked like, suggesting that they were small and plain, with no flashy petals. These simple blooms call into question most preconceived conceptions about what defines a flower.

To explore what the earliest primitive angiosperm could have looked like, I traveled to England and visited paleobotanist Chris Hill, who had previously worked at the Natural History Museum in London. Hill took me into the countryside to Smokejacks Brickworks, a quarry located south of London. Smokejacks is a hundred-foot-deep (30-meter-deep) hole in the earth the size of several football fields that has been producing much more than raw brick material. Its rust-colored clays have retained hundreds of fossils from around 130 million years ago. We marched to the bottom of the quarry, got down on our hands and knees, and started digging.

Hill quickly lifted a piece of mudstone. He showed it to me and pointed to an impression of a little stem that ended in a basic flower. The fossil looked like a solitary sprout taken off a broccoli head. The world’s first flower? Hill, who discovered his first fossil here in the early 1990s, described it as more akin to a floral precursor. He formally called it Bevhalstia pebja, combining the names of his closest comrades.

Through my magnifying lens, the Bevhalstia fossil seemed little and straggly, like an unimpressive plant growing in the water along the side of a pond, which is where Hill thinks it originated.

“Here’s why I think it could be a primitive flowering plant,” Hill went on to say. “Bevhalstia is unusual and cannot be assigned to any current plant family. So we begin by comparing it to what we know. Some current water plants’ stems have the same branching patterns as Bevhalstia, with small flower buds growing at the tips of specific branches. Bevhalstia also closely resembles a fossil discovered in 1990 by American paleobotanists Leo Hickey and Dave Taylor. That specimen, a little 120-million-year-old plant from Australia, produced leaves that were neither fernlike nor needlelike. Instead, they are veined, much like contemporary blooming plant leaves.

More importantly, Hickey and Taylor’s specimen has petrified fruits that formerly had seeds, which Hill intends to connect with Bevhalstia. Both plants lack distinct flower petals. Both are more basic than the magnolia, which was recently dethroned as the earliest bloom but remains an old lineage. And both, together with a recent discovery from China known as Archaefructus, have bolstered the theory that the earliest blooming plants were modest and unassuming.

Early angiosperms, like all pioneers, sprang from the edges. In a world dominated by conifers and ferns, these botanical intruders gained a foothold in places of ecological disturbance, such as floodplains and volcanic zones, and adapted fast to new conditions. According to fossil evidence, the early blooming plants were herbaceous, which means they lacked woody components. (According to recent genetic studies, the majority of ancient angiosperm lineages had both herbaceous and woody plants.) Unlike trees, which take years to grow and produce seed, herbaceous angiosperms live, reproduce, and die in short periods of time. This allows them to swiftly establish fresh territory and maybe adapt quicker than their rivals, which may have contributed to their variety.

While this herbaceous nature may have provided them an advantage against slow-growing woody plants, the flower was the angiosperms’ secret weapon. Simply put, a flower is an angiosperm’s reproductive system. Most flowers have both male and female components. Reproduction starts when a flower releases pollen, which are small packets of genetic material, into the air. These grains eventually fall to rest on another flower’s stigma, a small pollen receptor. In most instances, the stigma is located atop a stalk-like structure known as a style, which protrudes from the center of the flower. Moisture softens the pollen particle, which releases proteins that chemically determine if the new plant is genetically suitable. If this is the case, the pollen particle germinates and forms a tube that travels through the style and ovary to the ovule, where fertilization happens and a seed starts to develop.

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