Tree number 12 on the Hickory Hills Trail is an example of Lichens. Lichens are two plants, algae and fungi, living together. The algae make food and the fungi provide moisture and support. If separated, they would both die - this is called a symbiotic relationship. Not sure if the Lichens are still here - the trail markers are old and I had to wait while the rangers dug out some information on them - but the cache is here.