Pandora is home to many planimals — plants with incipient nervous systems that display animalistic, especially predatory, tendencies. The Phalanxia is among this category of creatures. Sensory tendrils drift down from the stem, which is crowned by an array of bracts tipped with needle-like spines. Beneath these, tubular flowers grow where the seeds of the plant are produced.

When the Phalanxia detects movement via its sensory tendrils, the plant rapidly accumulates stored gases in the needle bracts, which causes the spines to eject with considerable force. The spines themselves carry a fast-acting neurotoxin that paralyzes potential threats within seconds and kills within minutes. This toxin is immediately deadly to smaller creatures, but a precise shot in an unlucky place can even bring down larger animals and Na’vi. The decomposition of fallen prey in turn fertilizes the grove of Phalanxia, nourishing the plants.

As a reward for the risk, Na’vi occasionally harvest Phalanxia spines for use in weaponry.