Lichens are amazing organisms, which are everywhere but often overlooked! They add splashes of colour and texture to tree trunks and branches, walls, rocks, pavements and gravestones. Lichens are complex life forms. They are made up of two or more very different life forms, living and working together; fungi, which provides the protective body of the lichen, and algae (sometimes cyanobacteria) inside the lichen, which uses energy from the sun with air and water to make food.

Lichens are very sensitive to air quality. The lichens in Jesmond Old Cemetery are affected by pollution (mainly nitrogen oxide) from two busy roads that run alongside it.

There are three main types of lichens:
Crusty (crustose) – very closely attached to whatever they are growing on, often looking like a splash of paint. If you look closely, you might see fruiting bodies that look like black dots or mini jam tarts (e.g. Lecanora sp). In Jesmond Old Cemetery you can spot them on old gravestones and on tree trunks. Some can be quite large.

Leafy (foliose) – usually quite flat but have leaf-like parts with distinct upper and lower surfaces (lobes). Some have tiny eye-lash like hairs on the underside of the lobes. In Jesmond Old Cemetery, the most conspicuous leafy lichen, Xanthoria parietina, is orange-yellow and grows in the tree canopy. It grows best where there are lots of nutrients around and is highly nitrogen tolerant. You’ll also find some small silvery grey ones (e.g. Physcia tenella) on tree trunks and branches.

Shrubby/Bushy (fructose) – attached at one point usually on trees, forming messy grey or brown mini shrubs, which stick out or hang down from the growing point. In Jesmond Old Cemetery they are uncommon because they are very sensitive to air pollution. If you are lucky you might spot the so called Oak Moss, Evernia prunastri, which looks like a bundle of stag antlers.