Can you help identify lichen?

By Sarah West OPAL community scientist

Lichen can grow anywhere from trees to gravestones

You might not know it, but you see lichens every day. They are amazing things that are half fungi, half algae.

They grow on trees, pavements, gravestones, fence posts, and I've even noticed a few growing on the plastic window frames on my house in York. Once you start looking out for them, you'll see them everywhere!

They are many different types of lichen. Some species are brightly coloured, others are more drab in appearance, and at first glance you might think they are just a round patch where the stone or wood has changed colour.

However closer inspection may reveal tiny fruits on the lichen that look like jam tarts or wine gums. On the other hand, you might be disappointed, and find that the round patch is in fact chewing gum!

Lichen can help scientists learn more about air quality

Lichens are sensitive to changes in their environment, and scientists use lichens as a way of finding out whether air is polluted or clean.

Some species are only found where the air is very clean, whilst other species thrive in the nitrogen-rich, less clean air that we find in our cities. By looking at the types of lichen that are in your local area, you can find out whether the air quality is good or bad.

A guide to some of the lichens that are sensitive to air pollution has been developed as part of the OPAL Air Survey.

We want you to go and look at four trees in your local area, this could be a garden, park or stray, and tell us which lichens you find on them. We will use your results to build up a map of local air pollution across England.

The Air Survey is part of the OPAL project, which is funded by the Big Lottery Fund. OPAL is running projects all across England, but I'm based at the University of York, and I'm responsible for OPAL activities in Yorkshire and the Humber.

You can find out more about the project and get involved by emailing me.

Or you can visit the OPAL website for more information.