Lunar love (Image: Kristina Bolinder)

It’s the only known plant species that relies on the lunar cycle for survival – and we found out by complete accident.

At night, Ephedra foeminea, a non-flowering relative of conifers and cycads, secretes small translucent globules of sugary liquid to attract nocturnal pollinating insects. The globules are like tiny beads oozing out from cone-shaped female organs, where the seeds are produced. If a pollinator lands on a globule, any pollen it is carrying is absorbed via the liquid into the female cone, where it fertilises the seed.

It took a while for researchers to notice the plant was following the moon. While studying other Ephedra species, Catarina Rydin and Kristina Bolinder of Stockholm University in Sweden had found that pollinator-attracting globules appeared on these plants around the same time every year. But when they revisited Ephedra foeminea plants in Greece and Croatia in 2013 to observe their pollination, they were flummoxed to find no globules.


“After a useless week in Greece without any pollinators to observe, we were in a really bad mood, and decided to go for a dinner instead of visiting the field site again,” says Rydin. “Then, all of a sudden, there was a eureka moment, perhaps from seeing the moon on photos from a previous year, and contrasting it with the darkness we’d experienced so far at the field site.”

Although the idea of a link between Ephedra foeminea pollination and the lunar cycle started as a joke, they sifted through all their data in search of a pattern which they could follow up on during their next visit. “It all fitted, and all we had to do was wait for 2014’s full moon in July to see if that was what the plants were waiting for, and it absolutely was,” says Rydin.

Diamonds in moonlight

The globules appeared exactly when the moon was full, but a wind-pollinated relative showed no lunar correlation.

The activities of many animal species are known to be linked to the full moon, including various crabs, seabirds, dung beetles and corals. But in the plant world, Ephedra foeminea may be the first.

“To the best of our knowledge, this is a first,” says Rydin. “At night, the many pollination drops glitter like diamonds in the full moonlight, a spectacular sight also for the human eye,” she and Bolinder report.

Exactly how the plants know when the moon is full isn’t yet clear. Perhaps they can sense the intensity of the moonlight or gravitational changes.

Rydin thinks the species might be vulnerable to human light pollution, although they have not investigated this yet. “Our feeling is that the insect-pollinated species is steadily growing further and further away from villages compared with wind-pollinated species,” she says.

Journal reference: Biology Letters, DOI: 10.1098/rsbl.2014.0993