Research Summary
Flowering plants, ranging from corn, wheat, rice, and potatoes to maple, oak, apple, and cherry trees...and even the foul-smelling corpse flower and voodoo lily, form the foundation of Earth's ecosystems and are essential to human life.
A new study, published April 24 in the journal Nature, draws on the genetic data from 9,506 species, as well as examining 200 fossils, to provide the most in-depth understanding yet of the evolutionary history of flowering plants, known as angiospermsâ€"the largest and most diverse group of plants. The study details how angiosperms emerged and came to dominate during the age of dinosaurs and how they changed over time.
Scientists have uncovered a new tree of life for angiosperms, covering 15 times more flowering plant diversityâ€"nearly 60 percent moreâ€"than the closest comparable study.
"It's a quantum leap forward in our understanding of plant evolution," says study senior author William Baker, botanist at the Royal Botanic Gardens, Kew (RBG Kew) in London.
Angiosperms, plants that produce flowers and enclose their seeds within fruits, comprise around 330,000 species and make up about 80 percent of all plants on Earth. They include all major food crops, grasses, most broadleaf trees, and most aquatic plants. Their closest relatives are gymnosperms, a group that predates them on Earth and includes conifers and some others, with just over 1,000 species.
Key Findings
The study identifies two major bursts of diversification among angiosperms. The first happened 150-140 million years ago early in their existence during the Mesozoic Era, with 80 percent of angiosperm lineages arising during that time. The next occurred about 100 million years later in the Cenozoic Era after the extinction of the dinosaurs and the rise of mammals, amidst cooling global temperatures.
"Angiosperms have many more structural adaptations that give them advantages over gymnosperms, but chief among these are traits that contribute to reproductive success," Baker says.
Gymnosperms and angiosperms both have seeds, but flowering plants enclosed their seeds to protect them from drying out and helped them thrive in a wider range of environments, from tropics to deserts to Antarctica.
Angiosperms also evolved flowers, a structure that allows them to form relationships with pollinators, particularly insects, while gymnosperms generally rely on wind for pollination. Angiosperms have evolved a huge diversity of fruits, which enable effective seed dispersal.
"With these innovations, angiosperms became pretty much unbeatable," Baker says.
Importance of Flowering Plants
Flowering plants provide the majority of calories humans consume from grains, fruits, and vegetables, and they indirectly feed livestock. They also delight us with their beauty, from fields of sunflowers to bouquets of roses to fragrant lily of the valley.
"They are a source of many medicines and hold potential solutions to global challenges such as climate change, biodiversity loss, human health, food security, and renewable energy," Baker says.
The study could help scientists better understand disease and pest resistance in angiosperms and guide potential new medical applications, such as for fighting malaria.
"Combining our tree of life with extinction risk assessments for each lineage allows us to prioritize lineages for conservation based on their uniqueness," says RBG Kew botanist Alexandre Zuntini, the study's lead author. "This is critically important for humanity, as these lineages may hold chemical compounds or even genes that could prove useful for our own survival."