What is a lichen? It’s a combination of 2 things: fungi and algae or fungi and cyanobacteria.

North America has 3,600 species of lichens and worldwide there are over 14,000 with some estimates totalling 25,000! They are found on soil, on rocks, and on trees mainly, but they can grow on any undisturbed surface. They are very slow growing, sometimes only 1mm a year and like other slow growers, they have long lives. They are able to withstand extreme environmental conditions. UC Berkley’s website states that fossil records are hard to find but the oldest confirmed one is 400 million years found in Scotland.

Lichens serve a number of purposes. They provide nesting materials for birds; food for birds, mammals, insects, snails; camouflage for amphibians. It is a great indicator of air quality and helps by recycling airborne chemicals into the soil – this can be a good thing or bad thing, depending on the chemical. Lichens are used in a variety of herbal remedies; their antibacterial qualities are also being studied for use in modern medicine as they can produce up to 500 different chemical compounds. They have also been used as a natural dye.

I’ve done my best to identify these lichens accurately, seeking expert advice at times. Please let me know if you find any inaccuracies. I’ve also used these resources for the information about the individual species as well as general info about each category.

Candelaria concolor – Candleflame Lichen
Flavoparmelia carperata – Common Greenshield
Physcia stellaris – Star Rosette Lichen
Xanthoria hasseana – Poplar Sunburst Lichen