• Breathtaking autumn colors in Bering Land Bridge National Preserve

    Bering Land Bridge

    National Preserve Alaska


Anyone who has learned about lichen has probably heard some variation of the old (and really bad) joke: Why did the fungus marry the algae? Because they took a lichen to each other! While it may cause to you groan, it does help to remember the formation of lichen. Through a symbiotic relationship, algae and cyanobacteria feed the fungus on which they live by converting the sun's energy into sugars by way of photosynthesis.

There are three main categories of lichen: Foliose (leaf-like, flattened growth where the lobes have both upper and lower surfaces), Crustose (grows tightly to a substrate, like a crust), and Fruticose (hair-like, shrub-like, or stalk-like). Lichens can be useful for creating dyes, indicating air and substrate quality, and providing a food source for reindeer and caribou on the Seward Peninsula. Check out some of the most common lichen genera you'll find around Bering Land Bridge, below!

White, frilly cetraria lichen in the foreground with rocks and blue sky in the background

Cetraria Lichen

NPS Photo - Jason Gablaski


Cetraria are small to large foliose lichens with narrow or channeled lobes. Often yellow, brownish, or blackish, these are extremely common on the tundra and an important element in reindeer and caribou diets.

A close-up view of white, shrubby cladina lichen

Cladina Lichen

NPS Photo - Matt Jenkins


More commonly known as reindeer lichens, Cladina species vary widely and cover a wide range of land and habitats. These are typically shrubby, and whitish, greenish, or yellowish, found abundantly throughout the tundra. As the common name suggests, reindeer lichens are an important food source for local caribou and reindeer populations.

A patch of red and white cladonia lichen growing on grey rocks

Cladonia Lichen

NPS Photo


Not to be confused with Cladina, Cladonia lichens are stalk-like, and usually best identified by their cap of red fruit or their cup-like structure. Be aware though, these can be tricky -- all lichens with these characteristics fall under the Cladonia genus, but not all Cladonia have red fruit caps or that cup structure!

Bright orange, lumpy xanthoria lichen covering a rock

Xanthoria Lichen

NPS Photo


Lichens in the genus Xanthoria are easily recognized by their bright orange or yellow coloration. These are usually seen growing on rock faces around the Seward Peninsula, often where birds of prey hang out. Xanthoria love nitrogen-rich environments - and incidentally, bird feces contain high levels of nitrogen, so it can be used as an indicator of where you might find a raptor roost or nesting area.

Patches of crusty black umbilicaria lichen growing on tan rocks

Umbilicaria Lichen

NPS Photo


This medium to large black foliose lichen is commonly found on rock surfaces throughout the tundra. It can be identified by having a single point of attachment to the rock (like an umbilical cord), a dark upper side and pale underside.

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