Radiating

Arthonia radiata

Now that the garden has settled into its winter hibernation, I have had time to go through some of the many pictures that I took of things this past summer. And amongst them, I found this shot of a new species for the garden – the lichen Arthonia radiata. This crustose lichen (so-called because it looks like a crust, i.e. flat and inseparable from the bark) belongs to a group called the "script lichens". It gets that name due to those scribble-like black marks, which are its fruiting bodies (called apothecia). Those marks can range in shape from rounded to linear to star-like; the latter shape gives it the common name of "asterisk lichen". Each colony is surrounded by a thin dark line, which is an area of the thallus (the "body" of the lichen) that contains only fungal hyphae and no algae. The thallus itself can range from white through pale grey or fawn to brown in colour, and is sometimes partially immersed into the bark. This is a common and widespread lichen across the British Isles, growing on the bark of smooth-trunked trees and shrubs.