A recent PLoS One paper by Dejean et al documents a novel predatory behavior of Azteca andreae. Rather than waste words explaining it, here’s a video:
The key innovation is that the plant is woolly. That is, the underside of the leaves are covered in fibrous hairs not unlike the fuzzy side of Velcro®. When paired with tarsal hooks on the tips of ants’ feet, the whole assembly behaves as such, and the ants can snare heavy prey without becoming dislodged from the leaf.
By growing structures for the ants’ footholds, the plant helps the ants catch insects that might otherwise consume it. It’s an ingenious form of self-defense.
source: Dejean A, Leroy C, Corbara B, Roux O, Céréghino R, et al (2010) Arboreal Ants Use the “Velcro® Principle” to Capture Very Large Prey. PLoS ONE 5(6): e11331. doi:10.1371/journal.pone.0011331