A Journey Through Time

Flowering plants, from the familiar corn and wheat to the majestic oak and delicate rose, are the cornerstones of Earth's ecosystems and essential for humankind. A new study, based on the genomes of 9,506 species and 200 fossils, provides the deepest understanding yet of their evolutionary history.

The research reveals how flowering plants, known as angiosperms, emerged and became dominant during the age of dinosaurs, and how they have continued to evolve over time. The scientists constructed a new tree of life for angiosperms, encompassing 15 times more species than previous studies.

"It is a massive leap forward in our understanding of plant evolution," says botanist William Baker of the Royal Botanic Gardens, Kew (RBG Kew) in London, senior author of the study published in the journal Nature.

Angiosperms, with their enclosed seeds and diverse fruits, comprise about 80% of the world's plants. They include all major food crops, grasses, most broad-leaved trees, and most aquatic plants. Their closest relatives are the gymnosperms, a group that includes conifers and has about 1,000 species.

The study identified two major diversification periods for angiosperms. The first occurred around 150-140 million years ago, with 80% of major lineages arising during this time. The second happened about 100 million years later, after the demise of the dinosaurs and the rise of mammals.

"Angiosperms have many structural adaptations that confer advantages over gymnosperms, but chief among these are those contributing to reproductive success," says Baker.

Enclosed seeds protect angiosperms from dehydration and enable them to thrive in diverse environments. They also evolved flowers, attracting animal pollinators, and a high diversity of fruits for effective seed dispersal.

"With these innovations, angiosperms have become invincible," says Baker.

Flowering plants provide the majority of calories consumed by humans, directly and indirectly. They also enthrall us with their beauty and fragrance, and hold potential solutions to global challenges like climate change and food security.

This study could help scientists understand disease and pest resistance in angiosperms and discover new medicinal uses. It also allows for prioritizing lineages for conservation based on their uniqueness, which may hold valuable chemical compounds or genes for human survival.