I live in the chalk hills of the South Downs. On my daily walks over these hills I am always greeted by familiar alkaline-loving flora.
But if I head a little north there are areas of acidic soil in places Duncton and Lavington Common. The contrast as soon as I step into these areas is rewarding. There is sand underfoot and old friends like heather all around.
One of my favourites is a common lichen called Cladonia portentosa. It is sometimes nicknamed ‘reindeer moss’ or ‘reindeer lichen’, but purists argue that the only one truly deserving that name is a similar but different lichen called Cladonia rangiferina.
Portentosa (pictured) favours acidic, sandy heaths and dunes and is common in lowland areas. Rangiferina is more common on higher ground.
I like portentosa for two reasons. It is beautiful close up and from afar. But it is also a guarantee of a certain type of habitat. When I see this lichen I know have reached acidic open country. It is a distinct wilderness marker and promises a wild feel to an area, even if civilization remains within earshot.
Birch trees share a love of this terrain and I know I will see a birch tree whenever lifting my eyes from this lichen.