VOA科学技术2024--New Research Learns Evolution of Flowering Plants（在线收听）

Flowering plants are very important to Earth's ecosystems. They are necessary for life on Earth.

Flowering plants are also called angiosperms. They are the largest and most diverse plant group. Flowering plants include corn, wheat, rice and potatoes to maple, oak, apple and cherry trees.

New research based on genome data for 9,506 species of flowering plants provides the deepest understanding yet of their evolutionary history. The research explains how angiosperms appeared and became widespread during the age of dinosaurs. It also offers explanations for how such plants have changed over time.

The team of scientists created a new tree of life for angiosperms. A tree of life is a tool that biologists use to see the evolutionary relationships among plants, animals and other life forms. Their new tree of life covers 15 times more kinds of flowering plants than the closest comparable study.

"It is a massive leap forward in our understanding of plant evolution," said William Baker. He is a plant expert with the Royal Botanic Gardens, Kew, in London. He is senior writer of the research study, which appeared last week in the publication Nature.

Angiosperms are plants that produce flowers and produce their seeds in fruits. They are made up of about 330,000 species. About 80 percent of the world's plants are angiosperms. They include, among others, all the major food crops, grasses, most large-leaved trees and most aquatic plants.

Their closest relatives are the gymnosperms, a group that came before them on Earth.

The study identified two periods of diversification among angiosperms. The first one occurred around 150 million to 140 million years ago during the Mesozoic era. At that time, 80 percent of major angiosperm species arose. The next one happened about 100 million years later during the Cenozoic era, after the extinction of the dinosaurs and the rise of mammals. That period saw decreasing world temperatures.

Baker said angiosperms are more successful at reproducing than gymnosperms.

Gymnosperms and angiosperms both have seeds. But the flowering plants have enclosed seeds that protect them from dehydration. This permits them to survive in a wider range of environments, from deserts to Antarctica.

They also evolved the flower, a structure that permitted them to form relationships with animal pollinators, especially insects. Gymnosperms usually depend upon the wind for pollination. Angiosperms evolved a high diversity of fruit types, permitting effective seed spread.

Flowering plants provide most of the calories that humans eat, from grains to fruits to vegetables.

"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," Baker said.

The study could help scientists better understand disease and pest resistance in angiosperms. And the research could help find new medicines.

Alexandre Zuntini is Royal Botanical Gardens botanist and a lead writer of the study. He said that some plant "lineages may hold chemical compounds or even genes that can be useful for survival of our species."

Words in This Story

ecosystem - n. everything that exists in a particular environment

diverse - adj. different from each other

evolution - n. a theory that the differences between modern plants and animals are because of changes that happened by a natural process over a very long time

leap - n. to suddenly increase by a large amount

aquatic - adj. living or found in or near water

enclose - v. to surround

dehydrate - v. to remove water or moisture from

source - n. someone or something that provides what is wanted or needed

challenge - n. to say or show that may not be true, correct, or legal

botanist - n. a branch of science that deals with plant life

lineage - n. the people who were in someone's family in past times