What am I ?????

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

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

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)

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

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 1000-4500 yrs old. Longevity attributed to ability to withstand long periods of drought and resume growth when water becomes available.

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

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

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