Study: How Plants Evolved to Weather the Cold

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 results are published Dec. 22, 2013, in the journal Nature. Early flowering plants are thought to have been woody—which maintain 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.