Flowering plants, also known as angiosperms, are a cornerstone of Earth’s ecosystems and are essential for human survival. They include a diverse range of plant life, from crops such as corn, wheat, rice, and potatoes, to trees like maple, oak, apple, and cherry, as well as flowers such as roses, tulips, daisies, and dandelions. Even the unusual corpse flower and voodoo lily are part of this group. A new study based on genome data for 9,506 species and an examination of 200 fossils provides the most comprehensive understanding to date of the evolutionary history of flowering plants.
The study, published in the journal Nature, details the appearance and rise of angiosperms during the age of dinosaurs and their evolution over time. The researchers devised a new tree of life for angiosperms, covering 15 times more types of flowering plants – nearly 60% of them – than the nearest comparable study.
“It is a massive leap forward in our understanding of plant evolution,” said William Baker, a botanist at the Royal Botanic Gardens, Kew (RBG Kew) in London and senior author of the research.
Angiosperms, plants that produce flowers and generate their seeds in fruits, encompass about 330,000 species and comprise about 80% of the world’s plants. They include all the major food crops, grasses, most broad-leaved trees and most aquatic plants. Their closest relatives are the gymnosperms, a group that preceded them on Earth and includes conifers and some others, with a bit more than 1,000 species.
The study identified two pulses of diversification among angiosperms. The first one occurred around 150-140 million years ago at the dawn of their existence during the Mesozoic era, with 80% of major angiosperm lineages arising during that time. The next one happened about 100 million years later during the Cenozoic era, after the demise of the dinosaurs and the rise of mammals, amid decreasing global temperatures.
“Angiosperms have many structural adaptations that confer advantages over gymnosperms, but chief among these are those contributing to reproductive success,” Baker said.
Gymnosperms and angiosperms both have seeds, but the flowering plants have enclosed seeds that protect them from dehydration and enable them to prosper in a wider range of environments, from tropics to deserts to Antarctica. They also evolved the flower, a structure that allowed them to form relationships with animal pollinators, especially insects, while gymnosperms usually rely upon the wind for pollination. Angiosperms also evolved a high diversity of fruit types, permitting effective seed dispersal.
“With these innovations, angiosperms have become invincible,” Baker said.
The new understanding of angiosperm evolution can help scientists in various ways. The study could help scientists better understand disease and pest resistance in angiosperms and navigate potential new medicinal uses – for example, to combat malaria.
“Combining the tree of life with extinction risk assessments for each lineage allow us to prioritize lineages for conservation based on their uniqueness,” said RBG Kew botanist and study lead author Alexandre Zuntini. “This is extremely important for mankind, as these lineages may hold chemical compounds or even genes that can be useful for survival of our species.”
Flowering plants provide the majority of calories consumed by humans and have enthralled people with their beauty and pleasant fragrance. They are sources of many of our medicines and hold potential solutions to global challenges, such as climate change, biodiversity loss, human health, food security and renewable energy. The new study sheds light on the remarkable evolutionary journey of angiosperms and highlights their continued importance to our world.
