01/10/2012 12:08 pm ET Updated Jan 10, 2012

Worm-Eating Plant Uses Underground Leaves To Capture Prey

It may not look like much, but this little plant is a meat-eating killer. Scientists took awhile to figure that out because of its never-before-seen adaptation: instead of a gooey bug-trapping "mouth" like that seen in Venus Flytraps and other familiar carnivorous plants, little Philcoxia minensis sends some of its leaves under the sand, where they await passing worms to gobble up.

In a study published January 9 in Proceedings of the National Academy of Sciences, scientists detailed their discovery, which came after suspicions that the plant—native to the Brazilian savannah—was getting more nutrients than its small root would provide. It was unusual that some of its leaves—normally used to gather sunlight—grew underground, especially since they were covered with a sticky substance similar to secretions of other meat-eating plants.

For the study, the researchers tagged tiny nematode worms with nitrogen and watched as the plants absorbed it. There are several novel aspects to this finding. The underground leaves, naturally, are new, but so is the plant's dependence on nematodes. Co-author Rafael Oliveira told Science magazine, "When I first saw the results, I couldn't believe those underground leaves were actually eating nematodes."

The study has launched a conversation about the adaptation of meat eating in plants. It turns out that becoming a carnivore might not be such a complicated adaptation as we thought. Co-author Peter Fritsch said, "There is a balance point where if there are not enough nutrients or not enough light it can push a plant toward carnivorous syndrome.”

Fritsch expressed suspicions that there might be many more killer plants out there than we've identified, telling Nature magazine that “This leads to the question of whether there are other carnivorous plants out there in families not known for carnivory.”