Lichens On Tombs in Dulwich Village Old Burial Ground
A recent survey found 22 lichens here - 15 lending the patina of age to the stonework, seven growing on the trees.
Lichens (pronounced “like-ens”) are low-key, often very slow-growing organisms that pass under the radar, as it were, unless the observer has a hand-lens with which to appreciate their colours and coral-like beauty. In fact, our pavements may be sprinkled with grey-greenish blobs that could be mistaken for old chewing gum. But, here just a few miles from the City, their presence should be applauded. Because the presence of lichens - even in a spot like this - squeezed between roads on two sides of a triangle - is a good indicator of the quality of the air we breathe and a marker of a healthy environment. Following the Clean Air Act in the last century, lichens are recolonizing our towns and cities.
Lichens aren’t one living organism, but a pair which thrive together, taking what nutrients they need from the atmosphere or rainwater. One half of the partnership is a simple alga, or bacterium, which shelters within the growing tissue of a fungus. It is the fungus which gives lichen its visible structure. And the fungus is the dominant partner, exploiting the alga for the sugars it manufactures by photosynthesis.
Like the tomb stones on which they appear, the lichens belong to particular “families”, or biological type groupings, too. All the Burial Ground examples are of the crustose variety, so closely associated with the stone that they could not be easily removed without taking some of the stone surface off, too. The most common ones are the black, brown or white “stains” on the flat-topped chests (lichens belonging to the Verrucariales family). It is the fruiting bodies which give the colour - in this area, they are dark, but others nearby have attractive orange-red fruits on a dirty green background, seen in close-up.
On the large Smith Family Memorial, (west-facing vertical slab), there are orange and yellow lichens of the kind that favour basic limestones. One type is making a comeback after being very adversely affected by acid pollution. Two small plants are developing, one within the protective niche of the decorative frieze. A vivid green, powdery lichen (Psilolechia lucida) can be seen on the south-facing side of the top of the Boobyer Memorial.
Local lichen recovery is best seen on the Burial Ground’s gnarled Cornelian cherry. Look along its low, horizontal branches for the frilly, grey-green leafy plates of Phaeophyscia orbicularis (but please don’t pick them off!) You might catch sight of other types higher up - apple-green Flavoparmelia caperata, green-grey Physcia adscendens and P.tenella, mauvy-grey Physconia grisea and Xanthoria parietina, easiest to spot because it is bright yellow.
Remarkably, about one third of all the 2,000 species in Britain and Ireland are found in churchyards and burial grounds. Here, they play their part in a rich, intricate mosaic of flora and fauna in a green corridor where species of grass, moss, fungi, wild flowers, shrubs and veteran trees thrive. Insects, reptiles, birds and mammals go about their business undisturbed - from blackbird hunting a meaty worm to slow snail rasping a vegetarian meal from a lichen’s surface. All signs of life going on amid the Memento Mori resting in peace.
Angela Wilkes, Wildlife Group Chairman (with thanks to lichenologist Ishpi Blatchley)