Lichens are a symbiosis, a composite organism emerging from algae or cyanobacteria living among the filaments of fungi. Algae or cyanobacteria benefit by being protected from the environment by the filaments of the fungi, which also gather moisture and nutrients from the environment. The fungi benefit from the carbohydrates produced by the algae or cyanobacteria. Shield lichen are what we call a foliose lichen, there are two other types called crustose and fruticose. Foliose lichens are characterised by their flattened leafy shape, many of them like the Shield lichen have many layers. They are one of our most visible lichens in Otley, as they are fairly resistant to pollution and so are common in towns and cities. They are about 5mm wide and grow on branches, twigs and tree trunks.
By River Six