On acid rocks, rooftops, and limestone gravestones, lichens are quiet explosions, the elegant blemishes of age and decay. Poets deem them stoic, statements of the liquid passage of time. Scientists call them useful, indicators of clean air. Their growth can be analyzed to approximate the ages of natural masses, like flints and moraines.
Their history is richer than you’d imagine. In 18th-century France, women mixed lichen with lavender and rose essence to dust the inside of their wigs to keep bugs away. The unemployed in North Wales scraped lichens off rocks to sell to dye workers. Herbalists used the organisms to treat the body parts they resembled: Lung lichen was used for respiration issues, hair moss for an itching scalp, dog lichen for “mad dog bites.” Pacific Northwest First Nations and Indigenous peoples of Canada scraped lichens to eat as snacks, boil with fish, or add flavor to soups. The Iroquois washed lichens in water and ash to remove their bitter taste and then boiled them in grease.
Every lichen is a composite organism. There are four main types: fruticose (shrubby), foliose (leafy), crustose (crusty), and squamulose (scaly). The number of identified lichen hovers at 21,000. More than 1,000 types grow in the Pacific Northwest. Here are some native to our region:
Lung (Lobaria)
Lobaria is leathery with ridges and pits, resembling lung tissue. They are bright green when wet, olive brown when dry. Flip over one of the lobes to peer at a pale cream underside. Lung lichen thrives in damp old-growth forests like Washington’s North Cascades National Park, Colville National Forest, and Gifford Pinchot National Forest.
Sunburst (Xanthoria)
These clusters of wrinkly discs contain an infinity of orange: shades of goldenrod, cantaloupe, ochre, carotene, russet, marigold, tangelo. Xanthoria elegans — elegant sunburst lichen — has lobes. These mini-fireworks grow on rocks, such as those found along the coast of the Willamette Valley-Puget Trough.
Dog (Peltigera)
Peltigera are scaly with sometimes crinkly edges and white hair-like growths. They grow on soil, moss, trees, rocks, and damp turf. They can be found at the Columbia River Gorge.
Cup (Cladonia)
Cup lichen grows on moss, wood, soil, sand, and roof shingles. It sometimes sprouts brownish or red-fruiting knobs. You can find them crowding on rock outcrops in the Cascades or on sand dunes in Moses Lake. Noted for its cup shape, different species of Cladonia resemble vessels for different beverages: fimbriatas have cups with slim stems, like wine glasses; pyxidatas are stout, like schooners.
Beard (Usnea)
If you grew up plunging tent stakes into the forest floors on the Olympic Peninsula, you’ve likely encountered beard lichen — a mini-bush, lucent avocado green, identifiable by its tassels and elasticity. To understand its anatomy, loosely cup a bundle in your hand. With the other, pull apart a filament. It’ll split open, revealing its middle. That’s the medulla.