Posted on 15th February 2021 in Blog by Andrew Mitchell
Discover six different types of lichen that are susceptible to air pollution and are used as bio-indicators of air quality.
National Park Ranger Shaun Hackett shares six species of bushy (fruticose) lichen that are, with a little practice, easily identifiable.
These type of lichen are more susceptible to air pollution and are used as bio-indicators of air quality across the world. Lichens take their nutrients only from the atmosphere and many (though not all) are highly sensitive to airborne pollutants.
The species featured should be looked for on trees and old wooden structures. Look for examples the size of a golf ball as these will show their identifiable features more readily. Finding any of the six types is a good sign of good air quality; finding five / six would be excellent. Happy Hunting!
Evernia prunastri - Oakmoss
This lichen is commonly found growing on trees, especially Oak and flourishes in clean air environments but can tolerate low levels of pollution.
This species is used widely in the perfume industry as a `fixative` to give scent a longer life on the skin. It has antler type growth of flat forked branches pale yellow-green above and whitish below and a bushy loosely hanging form of growth.
Ramalina farinacea - Shaggy Strap Lichen
This is a bushy to pendant shaped (fruticose) Lichen with yellow-green to green-grey narrow flattened branches (1-3mm wide).
Scattered all along the branch edges are small oval to round discs (soralia) which are a helpful identifying feature. These are mainly found on trees and, when growing well, can be mat forming on tree trunks. This species can tolerate low levels of air pollution.
Usnea subfloridana – Beard lichen
A bushy shaped (fruticose) and compact lichen attached to a tree or wood by a single stem blackened at the base. It is yellow-green to grey-green in colour and much branched and adorned with clusters of minute round to oval discs (soralia).
A unique feature of this type of lichen is the stretchy white inner stem noticeable if pulled gently apart from either end. It is widespread and often common on trees and old fences where it can reach 7cm in size in good clean air conditions.
Ramalina fastigiata – Dotted Ribbon lichen
This is a tufted to erect well branched species with green (when wet) to grey irregularly flattened stems. (2-5cm high) These are always well covered with cream-coloured discs (apothia).
This is a widespread and common species, often found on well-lit tree trunks and branches.
Pseudervernia furfuracea - Antler Lichen
This is a tufted to pendant shaped species with light-grey branches the upper surface. It is often covered with small nodules ,while underneath it is black in colour, especially in older specimens.
It can be hard to spot among other lichen species, especially if present in small numbers. However, in clean air environments it grows well and can cover tree branches. It is commonly found on old gates or fence posts in upland areas.
Ramalina fraxinea - Cartilage lichen
A robust species is tufted when young but later more often pendulous with broad, sparingly divided strap-like branches grey-green to grey in colour. It commonly grows to 7cm but in suitable clean air conditions can reach 20cm often with noticeable discs (apothia) present too.
It is very sensitive to Sulphur Dioxide pollution and died out from many parts of the Country but has made a comeback in recent years and is now widespread across the National Park.
Often found on windy, exposed and well-lit sites especially on young Ash, Rowan and Sycamore trees. Find this and you’ve found some lovely clean air!