For well over a century, it was thought to be celibate. But now, 136 years after it was last caught in the act, British botanists have witnessed Nowell's limestone moss in the act of reproducing sexually. It's a glimmer of hope for this species on the verge of extinction.
Nowell's limestone moss (Zygodon gracilis) lives almost exclusively on ancient limestone walls in northern England. Its existence became increasingly tenuous as these walls deteriorated. Over the years, the moss have survived by vegetative propagation, in which new patches form from pieces broken off from older patches. But that's a slow process. A better option is "fruiting" by sexual reproduction--the production of spores that can be widely dispersed by wind.
As part of the U.K. government's biodiversity action plan, scientists went out last fall to update field surveys. "We spent many days walking along some very boring walls," says Fred Rumsey, a botanist at the Natural History Museum in London. "I was over the moon to find the moss fruiting." It had apparently beaten several odds. First off, the two sexes have to be within about 20 centimeters of each other. The moss's temperature and nutrition have to be just right for the sex organs to mature, too. Even then successful reproduction is not guaranteed: In some mosses, Rumsey noticed that ravenous mites had damaged the female sex organs. The team is currently preparing a manuscript on its findings.
The scientists now plan to do some matchmaking, moving males and females closer together to encourage more spore production. That approach holds promise, says Ron Porley of English Nature, a government-sponsored conservation group. But dislocating individual plants is "technically fiddly," he says, because they grow only reluctantly on a new piece of rock. "Getting this thing to establish is experimental and no one has ever tried it before," says Porley.