Longest lichen species

Usnea longissima, commonly known as old man's beard, ranks as the world's longest species of lichen, capable of growing up to 10 metres (32 feet 10 inches) in length. Lichens such as this are typically found in boreal forests and coastal woodlands in Europe, Asia and North America, where they grow in tree canopies, hanging down from high branches. U. longissima favours coniferous trees, especially in old-growth Douglas fir forests and near bodies of water.

Lichens such as old man's beard face a severe decline globally due to their extreme sensitivity to forest logging and air pollution, which can disrupt their metabolic processes and endanger their survival.

U. longissima has been utilized by humans for centuries, serving various purposes, including in anti-inflammatory traditional medicine and as a bedding material.

Lichens are compound organisms, consisting of a symbiotic association between a fungus and an alga and/or cyanobacteria, but they are named and classified according to their fungal constituents.