Mosses frozen in time come back to life

Being run over by a massive glacier is not a death sentence for some hardy Arctic plants. After hundreds of years buried under ice, mosses can regrow, biologists report May 27 in the Proceedings of the National Academy of Sciences.

The revived plants come from Canada’s Ellesmere Island, where the Teardrop Glacier has retreated since the end of a cold period in 1550 to 1850 known as the Little Ice Age. On recently exposed ground, Catherine La Farge of the University of Alberta in Edmonton and colleagues found clumps of mosses that looked dead. But among the brown tangles, the team noticed a few green sprigs.

The team took brown moss samples back to the lab and used radiocarbon dating to determine that they had lived about 400 years ago. Based on the glacier’s retreat rate, the researchers estimated the plants had been uncovered for less than two years.

Next, the team ground up some of the plants and gave them nutrients, water and light.”We didn’t do anything fancy,” La Farge says. From seven of 24 samples, a total of four moss species grew. The budding plants didn’t come from seeds or spores. In mosses, she says, any cell can be reset, almost like a stem cell, to grow a new plant.

Exactly how long a moss cell can stay viable is “anyone’s guess,” La Farge says. But the findings suggest that the regenerated mosses may help repopulate ecosystems after glaciers retreat.