Scientists find earliest ever "sleeping" plant

KUNMING, Feb. 16 (Xinhua) -- Nyctinasty, a plant's nastic movements responding to the alteration of day and night, like folding or raising leaves, could date back to 250 million years ago, according to an international research team's findings, published on Thursday in the journal Current Biology.

Similar to human beings' sleep motions, nyctinasty involves circadian rhythmic movements of leaves, of which the origin, evolutionary history, and functional benefits have been ambiguous, owing to a lack of fossil evidence, until researchers found fossils of plants showing damage inflicted by insects.

Led by Feng Zhuo, a researcher at southwest China's Yunnan University, the team of scientists compared the symmetrical patterns of insect-made damage on living folding leaves, with those on leaves of extinct plants dating back 250 million years.

They concluded that the fossil leaves were attacked when they were folded or "sleeping," which was the first evidence of foliar nyctinasty in fossil plants.

Moreover, they analyzed a large number of specimens and discovered that foliar nyctinasty evolved independently among diverse plant groups.