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• Evolutionary Essentials
 Flowering Plants Emerge
Can you imagine a world without flowers? Until around 140 million years ago, there were none. Then, early in the Cretaceous Period, the earliest flowering plants—or angiosperms—appeared.
Angiosperms are seed-bearing plants.
While other seed-bearing plants have exposed seeds, angiosperms produce seeds protected within a double-layered seed coat and enclosed within a fruit. (“Angiosperm” comes from the Greek angos, meaning “vessel,” and sperma, meaning “seed.”)
Flowers are how angiosperms reproduce.
Colorful flower petals attract pollinating insects in search of nectar. In fact, the evolution of new types of pollinating insects may have triggered angiosperms’ evolution, some 300 million years after the first land plants appeared. It wasn’t long before flowering plants became the most common and diverse plants on the planet.
 Flowering plants became diverse so quickly because of coevolution.
Essentially, when a species changes (evolves), this can trigger a change (evolution) in species that depend on it. Flowering plants rely on pollinators to fertilize their eggs. In turn, pollinators rely on flowers for their food source: nectar and pollen.
Because species can be so intimately connected, a change in one can result in a change in the other—a process called coevolution. And since pollinating insects were diversifying, flowering plants became more diversified, too.
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