Lichens and lichen photographs

A lichen is a stable combination of a fungus and a partner organism that uses light to photosynthesise. The partner is either an alga or a cyanobacterium. The fungus provides the fabric, and the partner, which lives inside, provides carbohydrates. About 1800 species have been recorded in Britain, with more species in the west and cleaner regions. Many lichens are difficult identify, chemical tests are often necessary, and some can only be identified by specialised experts but some of the species that are common in our area (and there aren't very many of them) are reasonably easy to recognise - so don't be put off! These photographs should help.

The best guide to lichens is LICHENS: An Illustrated Guide to the British and Irish Species by Frank S. Dobson (Richmond Publishing Company) but it is expensive at around £45.

You can download a list of all the species recorded in Scot's Gill and Borough Woods in 2004-2005 HERE (Excel spreadsheet 39 kb)

Below are photographs of some of the most easily recognised species that grow in the two Local Nature Reserves. You can scroll down the page or jump to individual species by clicking on the names.

Lecanora conizaeoides

Lecanora expallens

Melanelia fuliginosa glabratula

Xanthoria parietina and X. polycarpa

Cladonia chlorophaea - Common on soil, mossy banks, peat and rotting logs. The lichen consists of a mat-like blue-green thallus (Greek origin, meaning shoot) with structures like thick-stemmed trumpets sticking upwards, called podetia. The podetia are up to 3cm long.
(Cladonia means branch or twig-like, Dobson 2005).

Photo of podetia of Cladonia chlorophaea

Cladonia coniocrea - common in woodland on acid bark and decaying wood. Not common on soil. Often in urban areas, tolerant of SO₂ pollution. The lichen consists of a mat-like blue-green thallus with structures like small elephants' trunks sticking out, called podetia. The podetia are up to 3cm long.

Photo of lichen Cladonia coniocraea - small

Evernia prunastri - grey-green thallus consisting of bunches of straps fixed at one point to a tree branch or trunk. Underside whitish, often with green patches, in contrast to the similar-looking Ramalina. The straps are up to about 6cm long. Good specimens on lime trees along the roadside at St. Georges and it is often seen on fallen branches in winter .This species is growing better in the Morpeth area since the SO₂ was reduced. Dobson (2005) states that it was used as a fixative for perfume, as a dye and to make hair powder for wigs. Also used as flavouring for bread, as wadding for shotguns. Use by long tailed tits in nest making .

Hypogymnia physodes - has a grey-green lobed thallus with the undersides light to dark brown. The upper surface often has black dots towards the tips of the lobes. One of the commonest species one trees, stone and rocks. Good specimens on lime trees along the roadside at St. Georges. More resistant to SO₂ than most other species, Dobson (2005) says that it is decreasing in areas where acid deposition is decreasing. There is little sign of this happening in the Morpeth area as it seems to be fluorishing.

Lecanora conizaeoides - looks like a grey-green crust on tree bark or sometimes stone. It has small (1-2 mm) disc shaped reproductive structures called apothecia. It is the most SO₂ resistant lichen and before SO₂ was reduced, it was the only species that could be found in our town centres. It has decreased dramatically in the last decade, which is probably due to changes in bark chemistry. Nowadays it is mostly found on acid pine bark (as in the photograph, taken near St George's hospital).

Lecanora expallens - has a yellowish-white thallus and often looks like it has been dusted with flour. Note there are other, similar looking species in Northumberland. It is found in sheltered places on trunks, stumps and stone.

Melanelia fuliginosa glabratula - a bit of a mouthful! This has a greenish-brown, shiny thallus with lobes c. 3mm wide and notches at the apices. The underside is black. Mostly on tree trunks.

Parmelia sulcata - a very common species with a grey-blue thallus having overlapping lobes. The lobes have a fine white network that produce the reproductive structures, Underside black. Good specimens on lime trees along the roadside at St. Georges.. Note P. saxatilis is similar.

Physcia tenella - has a thallus of long greyish lobes about 1mm wide. This and a very similar species, P. adscendens, are found on nutrient rich substrates, tenella being mostly on bark and twigs. Often on twigs of trees used for perching by birds, you can see it on the sloe hedge near the start of the Borough Woods walk along with Xanthoria.

Ramalina farinacea - the thallus consists of grey-green to yellowish, flat to slightly concave, 1-3 mm wide branches that arise from a single 'holdfast' on a trunk or twig. The reproductive structures are whitish patches that look as if they have been dusted with flour, or 'farinose' hence the name.

Usnea subfloridana - 'Usnea' means rope-like or moss and both terms describe the thallus very well. The branches are up to about 10cm long and it is mostly found on twigs - look at fallen branches in winter.

Xanthoria parietina and X. polycarpa. Both of these species are greyish through to yellow and orange depending on the light. The discs in the photo are called apothecia and they release the reproductive structures, asci. It may be difficult to differentiate between the two species. Both are found where the nutrient levels are high, often on elder and where birds perch. They are expanding because of the amount of extra nitrogen that is being released from vehicles, fossil fuels and livestock.