On one of my regular walking routes there is a patch of forest where the pine trees are heavily adorned with silvery grey lichens that hang from the branches like feathery tufts.

It is a most compelling place, especially on winter mornings when the atmosphere is damp and the trees shrouded in mist. The aura here is almost primeval; silent air and patterns of grey. I’m not sure why this part of the wood should have so many lichens when nearby areas do not. But the reason doesn’t really matter, for the ambience they create is addictive and I suspect delivers an unconscious draw that makes this one of my favourite walks

Lichens are a bit like moss, all around us yet seldom remarked upon. They are also one of our more fascinating lifeforms, for they actually consist of two (or more) organisms rather than one. It’s a concept I find difficult to get my head around, but in simple explanatory terms lichens are partnerships between algae and fungi. But they are so closely interwoven with each other that they appear as one.

It is a mutually beneficial relationship where the alga produces food through photosynthesis while the fungus uses its inherent properties to create structure and support, as well provide mineral nutrients and store water so as to prevent desiccation.

So, although the numerous types of lichens are classed as individual species, they are technically a combination of species. Lichens are incredibly successful and survive in some of the most inhospitable places on earth. Climb to the top of the Cairngorms and there will be colourful lichens on the rocks. You’ll find them too on boulders by the seashore where some are tolerant of salt spray and even brief immersion in saltwater.

Indeed, once your mind-set moves into lichen mode, you start seeing them everywhere. Any decent-sized rock will hold lichens, as will stone walls and trees. They even occur on garden lawns. Their variety is immense and they come in a multitude of different forms, some just as creeping encrustings on a rock (often in colourful oranges and yellows), and others with fluffy tendrils like the ones in my wood. There are around 1,800 different types of lichen in the British Isles.

An intriguing one is the aptly named map lichen, a low-spreading lichen found on rocks by the coast and which does indeed look like a map with its black squiggly lines set against a green background.

Lichens are important ecologically, offering shelter for a host of tiny invertebrates such as insects, spiders and molluscs, which in turn provide food for small birds like treecreepers and tits. Research has shown that woodlands abundant in lichens hold a greater diversity of wildlife than those where they are scarce. Birds often use lichens as a source of material to make their nests.

Lichens are also excellent indicators of clean and unpolluted air – and for that reason alone it is always satisfying to discover them thriving in your home area.