North America Native Plant

Washington Cracked Lichen

Botanical name: Acarospora washingtonensis

USDA symbol: ACWA2

Habit: lichen

Native status: Native to North America  

Washington Cracked Lichen: A Tiny Natural Wonder in Your Rocky Spaces Have you ever noticed small, puzzle-like patches on rocks in your garden and wondered what they might be? Meet the Washington cracked lichen (Acarospora washingtonensis), a fascinating organism that’s neither plant nor animal, but something wonderfully unique that calls ...

Washington Cracked Lichen: A Tiny Natural Wonder in Your Rocky Spaces

Have you ever noticed small, puzzle-like patches on rocks in your garden and wondered what they might be? Meet the Washington cracked lichen (Acarospora washingtonensis), a fascinating organism that’s neither plant nor animal, but something wonderfully unique that calls North America home.

What Exactly Is Washington Cracked Lichen?

Despite its name suggesting it’s a plant, Washington cracked lichen is actually a lichen – a remarkable partnership between a fungus and algae working together as one organism. This collaborative relationship allows them to thrive in places where most other life forms would struggle, particularly on bare rock surfaces where they form distinctive cracked, crusty patches.

The cracked part of its common name comes from its characteristic appearance: small, grayish to brownish patches that develop a distinctive puzzle-piece pattern as they mature. These cracks, called areoles, give the lichen its unique mosaic-like appearance that’s quite striking when you take a closer look.

Where You’ll Find This Native Gem

Washington cracked lichen is native to North America, with its natural range spanning across the western United States. You’re most likely to spot it in arid and semi-arid regions, including Washington state (which inspired its name), Oregon, California, and parts of the Southwest. It has a particular fondness for exposed rock surfaces in sunny, dry locations with plenty of air circulation.

Is Washington Cracked Lichen Good for Your Garden?

While you can’t exactly plant Washington cracked lichen like you would a flower or shrub, its presence in your garden is actually a wonderful sign! Here’s why having this little organism around is beneficial:

  • Environmental indicator: Lichens are sensitive to air quality, so their presence suggests you have clean air in your garden
  • Soil building: Over time, lichens help break down rock surfaces, contributing to soil formation
  • Natural beauty: They add subtle texture and interest to stone walls, rock gardens, and natural stone features
  • Low maintenance: Once established, they require absolutely no care from you
  • Year-round presence: Unlike many plants, lichens provide consistent visual interest throughout all seasons

How to Identify Washington Cracked Lichen

Spotting Washington cracked lichen is easier than you might think once you know what to look for:

  • Location: Look on exposed rock surfaces, stone walls, or large boulders in sunny, dry areas
  • Color: Ranges from light gray to brownish-gray, sometimes with slightly darker edges
  • Pattern: Distinctive cracked or puzzle-piece appearance with clearly defined borders between sections
  • Texture: Crusty and firmly attached to the rock surface
  • Size: Individual patches are typically small, often just a few inches across, though multiple patches may grow near each other

Creating Lichen-Friendly Spaces

While you can’t plant Washington cracked lichen directly, you can create conditions that might encourage its natural establishment:

  • Include natural stone features in your landscape design
  • Avoid using chemical treatments on or near stone surfaces
  • Ensure good air circulation around rocky areas
  • Choose locations with plenty of sunlight and minimal moisture retention
  • Be patient – lichens establish very slowly, sometimes taking years to become noticeable

A Word of Caution: Don’t Disturb!

If you’re lucky enough to have Washington cracked lichen naturally occurring in your garden, resist the urge to scrape it off or clean your rocks. These slow-growing organisms can take decades to establish, and removing them means losing a valuable part of your local ecosystem. Instead, celebrate their presence as a sign of a healthy, natural environment!

Washington cracked lichen might not be the showiest addition to your garden, but it represents something special – a living partnership that’s been perfecting the art of survival for millions of years. Next time you’re wandering through your outdoor space, take a moment to appreciate these tiny marvels quietly doing their part to make your garden a more diverse and interesting place.

Washington Cracked Lichen

Classification

Group

Lichen

Kingdom

Fungi - Fungi

Subkingdom
Superdivision
Division

Ascomycota - Sac fungi

Subdivision
Class

Ascomycetes

Subclass
Order

Lecanorales

Family

Acarosporaceae Zahlbr.

Genus

Acarospora A. Massal. - cracked lichen

Species

Acarospora washingtonensis H. Magn. - Washington cracked lichen

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