This is a section through the caudex (thickened stem) of an "ant plant" - Hydnophytum moseleyanum
. These plants live as epiphytes high in the canopy of tropical rain forests. They get plenty of water up there from the rain, but very few nutrients since they don't root in soil. So they have developed strategies to attract ants as little helpers! The plant grows enlarged stems with built-in chambers called domatia and little holes as entrances - perfect for ants seeking a nest high up in the trees. The ants in turn collect food and "pay" the plant with fertilizer, as well as a powerful sting to protect their home from marauding animals that would try to eat it. Co-evolution at its best - plant-insect cooperation in nature doesn't always have to do with pollination!