A team of researchers studying plants has assembled the largest dated evolutionary tree, using it to show the order in which flowering plants evolved specific strategies, such as the seasonal shedding of leaves, to move into areas with cold winters. The researchers, including University of Minnesota professor Peter Reich, will publish their findings Sunday, Dec. 22 in the journal Nature.
Early flowering plants are thought to have been woody— maintaining a prominent stem above ground across years and changing weather conditions, such as maple trees—and restricted to warm, wet tropical environments. But they have since put down roots in chillier climates, dominating large swaths of the globe where freezing occurs. How they managed this expansion has long vexed researchers searching for plants' equivalent to the winter parka.
"Freezing is a challenge for plants. Their living tissues can be damaged. It's like a plant's equivalent to frostbite. Their water-conducting pipes can also be blocked by air bubbles as water freezes and thaws," said Amy Zanne, the study's lead author and an assistant professor of biology in the George Washington University's Columbian College of Arts and Sciences.
More than 25 scientists with a wide variety of expertise worked together on this study.
"We wanted to understand more about how plants came to have evolved the traits that allow them to withstand cold," Reich said.