B. Lichens (ARTHOPYRENIACEAE)

The Arthopyreniaceae family of lichens consists of only a small handful of species.

NOTE: there are perhaps 120 families of lichen species. None of these have an English common name. We have therefore given them all the shared family name of ‘Lichens’. Although this is scientifically incorrect, it is better than saying something like ‘No English family name’. It also enables us to list all lichens on the search page by using this term.

Lichens - background information

A lichen is not a single organism, but a collaboration between a fungus and another organism that is able to manufacture nutrients that the fungus cannot. This association is called symbiosis, and the fungus combines with an alga or a cyanobacterium, both of which produce nutrients by photosynthesis. This combination results in a body called a thallus. Each lichen has a unique fungus, whereas some algae and cyanobacteria enter into association with many different fungi, algae being the more common partner of the two. Lichens have different properties to those of the component organisms, and many different structures and colours. Lichens grow on many types of surface, and in a variety of environmental conditions, but are nutritionally self-contained so are not parasitic. When seen growing along the branches of a tree, for example, they are simply using the tree for support. They may be found growing in some of the most extreme habitats on the planet. Their names may be misleading; ‘reindeer moss’ is a lichen, and not related to mosses, which are non-flowering plants.

Lichens have many growth forms of the vegetative body parts, or fungal filaments, collectively called the thallus. These forms are:

• fruticose (tiny, leafless branches)
• foliose (flat, leaf-like structures)
• crustose (crust-like flakes like peeling paint)
• leprose (powdery appearance)
• squamulose (tightly clustered, pebble-like forms)
• filamentous (hair-like)

October 2023 Lichen survey - acknowledgements

We are grateful to Neil Sanderson and Dr. Paul Cannon of the British Lichen Society, who freely gave their time and expertise to conduct a survey of the lichens in Heene Cemetery on 9th October 2023. The species listed here was identified during this survey.