When the World Was on Fire, Some Plants Decided to Work the Night Shift

During the Permian-Triassic mass extinction, global temperatures rose dramatically, most forests collapsed under extreme heat and vast areas of land went barren. The event, around 252 million years ago, remains the most severe biodiversity crisis in Earth's history: ocean species extinction rates exceeded 81 percent, terrestrial tetrapod genera suffered losses of 89 percent. Something, though, survived. And then took over.

Research led by the University of Leeds reveals how lycophytes, a group of ancient spore-bearing vascular plants, not only outlasted the extinction but came to dominate the recovering landscape. The study, published in Nature Ecology and Evolution, concludes that lycophytes survived by opening their stomata at night instead of during the day, storing CO2 as an acid and using it for photosynthesis after sunrise. The mechanism is called crassulacean acid metabolism, or CAM photosynthesis. Today it's rare, found mostly in desert plants built for heat and drought. The researchers believe lycophytes may have been the first plants to use it.

To reconstruct the physiology of plants dead for a quarter billion years, the team studied lycophytes' evolutionary relationships to identify their closest relatives, then analyzed carbon isotopes in fossils from South China spanning the late Permian to the Middle Triassic. Different photosynthetic pathways leave distinct isotope signatures, and lycophyte values diverged noticeably from other plants precisely during the extinction window.

For roughly five million years after the extinction, the planet stayed extremely warm. Lycophytes were ready for that. Most other plants were not.

Read the full story at University of Leeds, April 20, 2026

Hot Take: Nature ran through the usual plant survival strategies and failed. Lycophytes just rescheduled their workday and waited out the apocalypse.