This week’s #SpeciesOfTheWeek is a strange-looking lichen. Boreal Oakmoss (Evernia mesomorpha) is a common and widespread lichen in northern boreal and mixed forests. Like all lichens, it is not a single organism, but a mutualistic relationship between algae or cyanobacteria and fungi. Boreal Oakmoss can use any coniferous or deciduous tree as its substrate. While the name suggests oak trees, it has a preference for conifers. It is tolerant of most pollutants, so it can grow near urban areas. Boreal Oakmoss contains usnic acid, which can cause severe dermatitis, so it is recommended to avoid touching it. Its growth form is called fruticose, or shrub-like, with numerous forked, hanging branches. The branches contain the soredia, which are clusters of algal cells wrapped in fungal filaments, and are used for vegetative reproduction. This is a type of asexual reproduction where the soredia break off and are dispersed by wind, then grow into a new lichen after settling on a suitable substrate. Lichens don’t take nutrients from their host substrate, they collect their own water and nutrients from the air. An often overlooked part of the forest, lichens can be remarkable in their shapes and colours. Have you seen any cool lichens in the park?