Pseudocycas altissima

The Pandoran cycad bears an uncanny resemblance to cycads that occur throughout the Earth’s tropics. Cycads are ancient seed plants that are found in Earth’s fossil record as far back as 208 and possibly even 325 million years ago. They were common during the age of dinosaurs. (Read more)
Their broad distribution (and the presence of unique specimens on every continent), suggest that they might have been present even before the breakup of the supercontinent Pangaea. Although it is possible that identical life forms could have evolved on two separate planets, geological and atmospheric differences between Earth and Pandora have led some to speculate that cycads were transported to Pandora from Earth, possibly on a meteoroid chipped off from the Earth during the Yucatan asteroid strike. Given the remarkable chain of events that would need to occur, however, most xenobotanists and astronomers dispute the theory.

Cycads on Pandora live in close association with nitrogen-fixing organisms resembling anemone that grow on their trunks. They do not accumulate toxins in their tissues the way Earth cycads do and their seeds can be used as food by the Na'vi and ground up to make flour.

Since cycads have become rare on Earth, botanists are studying the possiblity of exporting specimens from Pandora. But it is believed that the symbiotic anemone would not grow in Earth’s atmosphere and that the nitrogen-fixing role would be accomplished by a blue-green algae in the roots, similar to Earth cycads. These algae produce a neurotoxin with symptoms similar to Lou Gehrig’s disease. Yet the beauty and rarity of the plant may still make it an attractive item in the horticulture trade.