Contrary to a thousand face cream（面霜，雪花膏） adverts¹, the secret of fertility might not be eternal（永恒的，不朽的） youth. Research by the ecologist Dr. Carlos Herrera, a Professor of Research at the Consejo Superior de Investigaciones Científicas in Seville, Spain has shown that the withering² action of flowers may have evolved to protect their seeds. His research is published in the October 2010 issue of the Annals of Botany (http://dx.doi.org/10.1093/aob/mcq160). Prof. Herrera said: "No one has paid much attention to the corollas（花冠） , collections of petals³ on a flower, when they shrivel（枯萎） . Their job is done, so it's no surprise they die. But if their job is done, why don't the petals simply drop off the plant? I thought there might be an advantage that kept the old corollas on the plant."

To test his idea, Herrera conducted a very simple experiment. He removed dead petals from some lavender（薰衣草） . Then he observed what happened to the seeds.

Prof. Herrera said: "The results for the lavender were striking. Normally you'd expect around 60% of the lavender fruits to ripen⁴. Without the withered⁵ petals around the fruit, only 40% ripened⁶. The dead petals seem to have formed a protective barrier around the fruit. In this case the barrier helps prevent attack by gnat⁷（小昆虫，小烦恼） larvae⁸（幼虫，幼体） who like to feed on lavender seeds."

He also tried the same experiment with some violas（中提琴） , but got a different result.

"For violas I found that the petals helped increase the number of seeds per fruit, but had no effect on ripening⁹. It's clear that the petals are doing something important for the plant after they decay, but it is a complex relationship that needs more study. Still, it shows there is a major role for petals to play on a plant, even after the bloom of youth has gone."