Lecanora

Lecanora chlarotera

One of the more common lichens in our garden is the widespread Lecanora chlarotera, which grows in small, roundish colonies on the trunks of many of our smooth-barked trees. It's a crustose lichen, which means it adheres closely to the bark on which it grows, and can't be easily separated. (The yellow-orange Xanthoria parietina growing beside it, on the other hand is a foliose lichen, easily lifted with a fingernail.) The thallus of Lecanora chlarotera is creamy to grey in colour, and can be either smooth or strongly warted. Many of the colonies in our garden (like those pictured above) have been overgrown by algae, giving them a slightly greenish cast. The abundant apothecia (the lichen's fruiting bodies) are buff to reddish-brown and surrounded by a thick thallus rim. In Britain, the description of these apothecia is "like a jam tart" — that is, like a pie with a rim of crust. To give you an idea of size, the biggest apothecia shown above are 1mm across, so if you're looking at this on a computer, the picture is much larger than life-sized! As would be expected, given our location (i.e. surrounded by well-fertilised farm fields), it does well on nutrient-enriched substrates. It's one of the early colonisers of young trees in semi-urban areas, such as new plantings in car parks or housing estates.