July 18, 2012 | 2
Moss, that cushy, moisture-loving ground cover, is more promiscuous than we thought. These plants might not have the sexy flowers of a peony, but according to new research, they do manage to attract small pollinators with a subtle sweet smell.
Previously, scientists had presumed that these primitive plants needed a layer of water for their sexual reproduction. Moss sperm have two tails and can swim quite well. This strategy, however, would mean a dispersal distance of about 10 centimeters tops—and would have given new meaning to the term “dry spell,” leaving female parts unpollinated without proper precipitation.
The new research, however, shows that the mosses, including Ceratodon purpureus (also known as ceratodon moss, fire moss or purple horned moss) and Bryum argenteum (silvergreen bryum moss) also use small insects called springtails (Foisomia candida) to spread their sperm. The mosses give off a slight odor, enticing the insects to crawl over them and pick up sperm, according to the findings, which were published online July 18 in Nature (Scientific American is part of Nature Publishing Group).
The researchers, led by Todd Rosenstiel, of Portland State University’s biology department, analyzed the volatile organic compounds expelled by sexually mature male and female moss plants and found that many of these chemicals were the same ones found in flowering plants. The male and female’s scents differed, and the female plant had a stronger, more enticing scent
But are these little bugs just a back up plan, in case of dry weather? The research team constructed various moss environments, giving some more or less water and more or fewer springtails. Even with plenty of water for sperm to swim through, the presence of springtails greatly increased the pollination rates.
This sexual reproduction strategy is actually quite remarkable, considering that the mosses and the microarthropods that apparently help pollinate them emerged as some of the first co-occurring forms of life on land. (The free-swimming sperm that can take advantage of a water layer are thought to be a holdover from their ancestors’ aquatic days.) So, these ancient organisms might have helped lay the foundation for the flashy flowers and pollinators that we have today. Next time you stop and smell the roses, don’t forget to pay a little thanks to the humble moss.