Bellicum pennatum

The warbonnet fern was aptly named for the primary use of this plant—as headwear during times of both war and peace. The similarity to Native American headwear made from feathers is obvious, as Pandoran colonists have noted.
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The most striking feature of the warbonnet fern is the iridescent blue of the leaves, which contain abundant anthocyanin pigments. These pigments are light-reactive chemicals that reflect blue light and that give color to blue and purple flowers and fruit. The warbonnet fern has evolved a close relationship with a particular species of forest bird, which is also a pale iridescent blue color and well camouflaged against the leaves of the plant. These birds feed on insects that are attracted to the blue leaves that have red lines radiating out from the center of the plant. Insects accumulate on the enlarged central apex or meristem, from which the leaves grow, and the small birds swoop in to feed.

It is fortunate that warbonnet ferns sprout readily from belowground buds because they are gathered and used regularly by the Na’vi. The dark nights are often illuminated by single leaves that have been mounted on trees with their glowing arrow-like pattern pointing to a special destination, reminiscent of earthly neon signs.