You have probably seen them everywhere - growing on logs, trees, the ground, and even tombstones.
If you spend any time in nature, especially on the Canadian Shield, you’ve likely walked on millions of these organisms, perhaps not giving it much thought. You may have never even noticed them, or if you have, you may not know much about them. Ubiquitous yet unfamiliar to the untrained eye, identifying lichen is not a feat for the faint-hearted.
Currently, hundreds of genera have been identified comprised of over 14,000 species of lichen. Approximately 3,600 species have been documented in North America, of which 2,500 have been found in Canada, and over 1,000 species in Ontario. The Frontenac Arch is a convergence point of species range limits, which boosts diversity of lichen as well as any other species. Studies involving lichen in the Frontenac Arch Biosphere have developed a protocol to survey rare lichen species, new and rare discoveries in Frontenac Provincial Park, and an action plan for species at risk including the endangered Pale-bellied Frost Lichen.
Lichen have been long described as a symbiotic relationship between algae, fungi and/or cyanobacteria, however more recent research reveals they are actually much more complex organisms containing tiny worlds composed of hundreds or even thousands of species. They vary wildly in their growth form, preferred substrate, texture, colour, chemical composition, sensitivity to air pollution and even edibility. Growth forms are crustose (lichen appears to be embedded or growing directly on a surface), foliose (leaf-like structure), and fruticose (three-dimensional structure). Most lichen grow slowly –fractions of millimetres per year – on a wide range of surfaces including live and dead tree bark, directly on the soil or on rocks. Some lichens such as Concentric Boulder Lichen will have very specific preferences, while others are not so picky.
"Porpidia Crustulata" (Concentric Boulder Lichen) is a crustose lichen with an affiliation for rocks with a high proportion of silica. Photo Credit: Abby Leavens, 2016
"Umbilicaria Mammulata" (Smooth Rock Tripe) is an apparently edible foliose lichen that grows exclusively on rock faces and can be processed into dye. Photo Credit: Abby Leavens, 2020
"Cladonia Cristatella" (common name: British Soldiers) is a pollution-tolerant fruticose lichen, growing on wood. Photo Credit: Kaitlyn Claus, 2020
Lichen are not just fascinating and flamboyant, they serve many functions. Some have traditional and current medicinal uses or have been used for food by Indigenous peoples and wildlife, including deer, moose and caribou.
Lichen have also been used in the fabrication of perfumes, dyes, acids and antibiotics. Northern Parula warblers use lichen as their primary nesting materials while hummingbirds use it to camouflage their nests. Lichen also play an important role in primary succession, preparing the terrain for other species to grow.
This blog has only scratched the surface of lichen identification, biology and ecology. If your interest is piqued and you are looking to delve deeper into the fascinating world of lichen, consider picking up a field guide or reading more by consulting the references listed below.
