1. What am I ?????

2. My name is “Golden Shields”, or “Xanthoria parietinar” in Latin
I am a lichen
I am found growing on rocks, walls and trees
I am one of the most common lichens found today in our towns and cities
I am even found in St Louis

3. What are lichens?
Unlike trees, grasses and flowers, lichens are not a single plant
They are actually composed of two organisms living together in a symbiotic relationship…
A blue-green algae which photosynthesises to make food, and a fungus which creates a “body” in which both partners live

4. Types
There are about 30,000 species of lichen worldwide, covering 8% of the land surface. There are 3 main types…
Crusty (crustose)
Leafy (foliose)
Shrubby (fruticose)

5. Why study lichens? They grow just about everywhere
They tell us about the health of our environment
They are very useful; - as recyclers of nutrients, providing homes for insects, humans extract dyes from them, eat them, use them as ingredients in drugs and cosmetics

6. LICHEN GROWTH Slow growing - most 1 mm/yr, a few up to 4 mm/yr.
Growth favored by high humidity, cool temperatures & low light.
Long-lived - Alpine-arctic lichens may be yrs old.
Longevity attributed to ability to withstand long periods of drought and resume growth when water becomes available.

7. USES OF LICHENS Food Dyes (litmus paper, Harris tweed)
Essential oils for perfumes, soaps
Bioactive compounds (antiviral, antibacterial)
Nesting/bedding material
Poisons

10. Lichens and air quality
Lichens are very sensitive to sulphur dioxide (SO2) pollution in the air – from industry and burning fossil fuels, especially coal
They absorb it dissolved in water
It destroys the chlorophyll in the algae preventing it from photosynthesising and killing the lichen.
Levels have fallen since the 1970’s

11. Nitrogen pollutants
Nitrogen compounds from traffic on roads and from intensive farming (fertilisers) have become major pollutants
Town and country areas can be affected