Walk through any park, street or woodland in Milton Keynes and you’ll find them quietly thriving: lichens. They are everywhere—on tree bark, stone walls, pavements, rooftops and even metal street signs. Yet most of us pass them by without a second glance.
Lichens are extraordinary organisms, formed through a partnership between fungi and algae (or sometimes cyanobacteria). This collaboration allows them to survive in places where few other life forms can. They play a vital ecological role: creating microhabitats for insects, providing food for slugs and snails, supplying nest material for birds and even helping us monitor pollution levels.
Fig. 1-6 A tree trunk holds far more than its bark suggests. Look closer and a living mosaic comes into view: the fine grey rosettes of Physcia tenella, the golden patches of Xanthoria parietina and the pale crusts of Lecanora chlarotera s.lat. Together they form a miniature community, showing how much life thrives on a single tree. Click on the images for a closer look. (Image credit: Jagoda Zajac)
But here’s the challenge—identifying lichens is notoriously difficult. Their shapes are subtle, their colours shift with moisture, and many species look deceptively alike. Proper identification often requires chemical spot tests to see if colours change, microscopic examination of spores or crystals in fruiting bodies, and even checking their reactions under ultraviolet light. To make things trickier, lichens are constantly being reclassified as scientific understanding evolves, with names and genera shifting in the taxonomic system. For beginners, this can feel daunting.
The good news? Some lichens are distinctive and easy to recognise once you know what to look for. These “gateway species” are perfect starting points for anyone curious about the hidden biodiversity around us.
Over the coming weeks, I’ll explore ten of the most common lichens found on trees in Milton Keynes. Each article will highlight a species, offering tips on recognition, ecological significance, and the stories they tell about our environment. I’m still learning myself but I hope this series will be a chance for both you and me to discover more about lichens together.
Jagoda Zajac, December 2025
Top photo: Ramalina fastigiata catching November sunshine (Credit: Jagoda Zajac)