To the surprise and delight of humans, ferns on Pandora seem to be very similar in appearance to those on Earth. Young leaves always emerge as a coiled fiddle neck shape, which is followed by the unrolling of the fern leaf. Ferns on Pandora have a feature not found on Earth, however. They form symbiotic relationships with algae, much as lichens do on Earth. The fiddlehead contains high concentrations of dark red algae that are highly toxic. On Earth a similar alga occurs in oceans under certain conditions, forming what is known as “red tide.”
At low concentrations the alga causes temporary hallucinations, while at high concentrations it can be fatal when ingested. The Na’vi collect the fiddlehead to extract the red pigment for use in paints. During the process they often absorb some of the algae into their bodies and enjoy a pleasant sensation of euphoria. However, they are careful to avoid ingesting large amounts.