Is it a Moss?

It is small, greenish, growing on a tree, but is it a moss? Unfortunately it's not, no matter how much it might envy our green mossy pals it doesn't qualify. This critter is a lichen. Lichens are symbiotic organisms which consist of a fungus and an alga, either blue-green or green. Typically fungi are saprophytic, meaning they feed on dead or decaying material and are not able to produce their own food. This fungus has a different lifestyle and is a farmer. No digging through the trash to find sugars for him. Instead this fungus houses a alga which it keeps happy by supplying water, air, and sunlight. With that combination of supplies that alga undergoes photosynthesis to produce sugars that the fungus uses to live. It is a pretty smart system and works out well for both of the partners. The lichen pictured here is Flavoparmelia caperata, the common greenshield lichen. This species typically grows on bark and can be found across the eastern United States. So when you are out looking for mosses keep an eye out for the lichens as well.