Lichens are common in NCR parks, where they are often conspicuous on old fence posts, stone monuments and the bark surface of living trees. Some species of lichens occur on bare soil or can be found on the dead branches of still standing trees. Lichens are what might be termed "composite" organisms–consisting of a fungus and an alga living together in an intimate partnership that allows both organisms to survive under conditions unsuitable for either partner alone. The greater part of the structure makes up the vegetative body of a lichen consists mostly of the fungal partner. Although not considered on this web site, anyone searching for fungi will also encounter lichens.