Pneumatophores

Xylocarpus granatum, an important timber species in Papua New Guinea (see Palms of Kikori), develops an abundance of aerial roots called pneumatophores. We don't really know why some trees (e.g. bald cypress, mangroves) produce these things. Some researchers think pneumatophores help trees get oxygen in flooded environments; others suggest that these aerial roots provide stability and structural support in mushy soils.  All I know is that they make walking through the forest extremely tricky when its flooded (see Wet Feet). [NOTE: The fact that  a tree doesn't die after its pneumatophores are removed would suggest that the stability in mushy soils hypothesis provides the most reasonable explanation for these structures].