North America Native Plant

Earth Lichen

Botanical name: Catapyrenium acarosporoides

USDA symbol: CAAC11

Habit: lichen

Native status: Native to North America  

Synonyms: Dermatocarpon acarosporoides Zahlbr. (DEAC5)  ⚘  Dermatocarpon novomexicanum (de Lesd.) Zahlbr. (DENO2)  ⚘  Endopyrenium bajadanae de Lesd. (ENBA)  ⚘  Endopyrenium novomexicanum de Lesd. (ENNO2)   

Earth Lichen: The Tiny Crusty Helper You Never Knew You Had If you’ve ever wandered through the arid landscapes of the American Southwest and noticed what looks like tiny brown patches scattered across the ground, you might have been looking at earth lichen (Catapyrenium acarosporoides) without even knowing it! This ...

Earth Lichen: The Tiny Crusty Helper You Never Knew You Had

If you’ve ever wandered through the arid landscapes of the American Southwest and noticed what looks like tiny brown patches scattered across the ground, you might have been looking at earth lichen (Catapyrenium acarosporoides) without even knowing it! This fascinating little organism is one of nature’s unsung heroes, quietly doing important work in some of our continent’s most challenging environments.

What Exactly Is Earth Lichen?

Earth lichen isn’t actually a plant at all – it’s a remarkable partnership between fungi and algae that creates what scientists call a composite organism. Think of it as nature’s ultimate roommate situation, where two very different life forms team up to survive in places where neither could make it alone. The fungi provide structure and collect moisture, while the algae photosynthesize and create food for both partners.

This particular species goes by several scientific aliases, including Dermatocarpon acarosporoides and Endopyrenium novomexicanum, which tells us that scientists have been scratching their heads about how to classify this little guy for quite some time!

Where Does Earth Lichen Call Home?

Earth lichen is a native North American species that has made itself at home primarily in the arid regions of the southwestern United States. You’ll typically find it thriving in desert environments where most other organisms would throw in the towel.

Spotting Earth Lichen in the Wild

Identifying earth lichen takes a keen eye since it’s not exactly showy. Here’s what to look for:

  • Small, crusty patches that appear brownish or grayish
  • Thin, almost paint-like coating on soil surfaces or rocks
  • Typically found in arid, open areas with little vegetation
  • Forms part of what’s called biological soil crust alongside other microorganisms

Is Earth Lichen Beneficial for Your Garden?

While you can’t exactly plant earth lichen in your backyard (it’s not sold at garden centers, and it wouldn’t survive most garden conditions anyway), its presence in natural areas is incredibly beneficial for the ecosystem. Here’s why this tiny organism deserves our respect:

  • Helps prevent soil erosion by creating a protective crust
  • Contributes to soil fertility by fixing nitrogen from the atmosphere
  • Provides habitat for microscopic soil organisms
  • Indicates healthy desert ecosystem conditions

Why You Probably Won’t See It in Your Garden

Earth lichen is perfectly adapted to harsh, arid conditions that most gardens simply don’t provide. It needs:

  • Very low moisture levels
  • Intense sunlight
  • Minimal soil nutrients
  • Little to no foot traffic or disturbance

If you live in the desert Southwest and happen to spot some earth lichen on your property, consider yourself lucky! The best thing you can do is simply leave it alone and appreciate this hardy little survivor for the ecological work it’s doing behind the scenes.

The Bottom Line

Earth lichen might not be the showstopper of the plant world, but it’s a fascinating example of how life finds a way to thrive in even the toughest conditions. While you won’t be adding it to your shopping list for weekend garden projects, understanding and appreciating these small but mighty organisms helps us better understand the incredible diversity and resilience of our native ecosystems. Next time you’re hiking in desert country, take a moment to look down – you might just spot some of these crusty little ecosystem engineers hard at work!

Earth Lichen

Classification

Group

Lichen

Kingdom

Fungi - Fungi

Subkingdom
Superdivision
Division

Ascomycota - Sac fungi

Subdivision
Class

Ascomycetes

Subclass
Order

Verrucariales

Family

Verrucariaceae Eschw.

Genus

Catapyrenium Flotow - earth lichen

Species

Catapyrenium acarosporoides (Zahlbr.) J.W. Thomson - earth lichen

Plant data source: USDA, NRCS 2025. The PLANTS Database. https://plants.usda.gov,. 2/25/2025. National Plant Data Team, Greensboro, NC USA