The previous record for viable regeneration of ancient flora was with 2,000-year-old date palm seeds at the Masada fortress near the Dead Sea in Israel.
The latest success is older by a significant order of magnitude, with researchers saying radiocarbon dating has confirmed the tissue to be 31,800 years old, give or take 300 years.
The study, in today's issue of the Proceedings of the National Academy of Sciences, described the discovery of 70 squirrel hibernation burrows along the bank of the lower Kolyma river, in Russia's northeast Siberia, and bearing hundreds of thousands of seed samples from various plants.
"All burrows were found at depths of 20-40 meters (65 to 130 feet) from the present day surface and located in layers containing bones of large mammals such as mammoth, wooly rhinoceros, bison, horse, deer, and other representatives of fauna" from the Late Pleistocene Age.
The permafrost essentially acted as a giant freezer, and the squirreled-away seeds and fruit resided in this closed world -- undisturbed and unthawed, at an average of -7 degrees Celsius (19 Fahrenheit) -- for tens of thousands of years.