Caves located in southwest China may be hiding vast gardens of ancient ice age nettles, preserved among the stalagmites for the last 30,000 years, reports New Scientist.

Seven new species of age-old nettle have already been discovered among the dark caves and gorges of the karst landscapes, located in the Guangxi and Yunnan provinces. One of the new species is so rare that it is limited to just 10 adult plants isolated in a remote grotto.

Researcher Alex Monro of the Natural History Museum in London, who identified the seven new species, thinks the caves have been acting as a time capsule, preserving the rare nettles since the time of a previous ice age.

"[The nettles may be] relics of a vegetation from a previous cooler climate that resembled that of the caves," he said.

Today the environment outside the caves is far too tropical to support nettles like these, which typically only survive in cooler, more temperate ecosystems. The only way for the plants to have found their way to the caves, then, is if they are descendents of ancient nettles which grew during a time when the climate was much different.

Where the newly discovered nettles come from is just part of their mystery. The other question is how they have managed to survive for so long in the near-black conditions of the caves.

"There must be something quite special about their photosynthesis," speculated Monro. "They probably activate the photosynthetic process very quickly, which enables them to take advantage of very short bursts of light, and they might go for slightly different wavelengths."

Because they are so isolated among the various caverns and grottos of the cave systems, two of the remarkable new species are already listed as "critically endangered," while the rest are either "endangered" or "vulnerable."

Bryan Nelson ( @@brynelson ) writes about everything from environmental problems here on Earth to big questions in space.

30,000-year-old nettle gardens discovered in Chinese caves
One new nettle species, found hidden among stalagmites and limited to just 10 adult plants, may be a relic from a past ice age.