So here’s my maple tree today. Looks pretty much the same as last week, doesn’t it? Until the ice and snow come, the tree won’t change very much. But that doesn’t mean you should stop reading. There’s still lots to explore and discover.
Today I’ve included a closer photo of the south-southwest side of the tree’s trunk. As you can see, the tree has some hitchhikers. That greenish gray stuff isn’t moss. It’s lichen.
What is lichen? Good question. It’s not a plant. It’s an unusual partnership between two life forms that have been hanging out for millions of years. And both organisms benefit bigtime from living together.
This particular lichen is a combination of a fungus and an alga (plural algae).
Lichen looks greenish because the alga partner contains chlorophyll. Like plants, algae use the chlorophyll to collect energy from sunlight. That energy combines with water and carbon dioxide in the air to make a sugary food called glucose.
A fungus can’t make its own food, but it’s bigger and tougher than algae cells, so it acts like a body guard. It grows around and between algal cells and protects them from the weather and some hungry critters. When algae live in a safe, stable environment, they can grow faster and make more food. So, like I said earlier, both creatures benefit.
Lichen doesn’t just grow on trees. And it isn’t always greenish gray. It can be red or orange or even yellow. If you start looking for lichen, you’ll see it in all kinds of places. So get outside and start exploring.