North America Native Plant

Willey’s Rim Lichen

Botanical name: Lecanora willeyi

USDA symbol: LEWI

Habit: lichen

Native status: Native to North America  

Willey’s Rim Lichen: A Fascinating Rock-Dwelling Organism in Your Garden Have you ever noticed those pale, crusty patches decorating the rocks in your garden or local hiking trails? You might be looking at Willey’s rim lichen (Lecanora willeyi), a remarkable organism that’s neither plant nor animal, but something wonderfully unique. ...

Willey’s Rim Lichen: A Fascinating Rock-Dwelling Organism in Your Garden

Have you ever noticed those pale, crusty patches decorating the rocks in your garden or local hiking trails? You might be looking at Willey’s rim lichen (Lecanora willeyi), a remarkable organism that’s neither plant nor animal, but something wonderfully unique. This native North American lichen adds subtle beauty to rocky landscapes while serving as a living indicator of your local ecosystem’s health.

What Exactly Is Willey’s Rim Lichen?

Willey’s rim lichen belongs to the fascinating world of lichens – organisms that are actually a partnership between fungi and algae working together in perfect harmony. Unlike traditional garden plants, lichens don’t have roots, stems, or leaves. Instead, Lecanora willeyi forms thin, crusty patches that seem to paint themselves directly onto rock surfaces.

This particular species creates circular to irregular gray or whitish patches that can range from barely noticeable to several inches across. The lichen gets its rim name from the distinctive raised edges that often form around its perimeter, creating subtle but beautiful patterns on stone surfaces.

Where You’ll Find This Native Beauty

Willey’s rim lichen is native to western North America, thriving in the arid and semi-arid regions where rocky outcrops and stone surfaces provide the perfect growing conditions. You’re most likely to spot it in areas with low humidity, excellent air circulation, and plenty of exposed rock.

Is Willey’s Rim Lichen Good for Your Garden?

While you can’t exactly plant Willey’s rim lichen like you would a flower or shrub, its presence in your garden is actually a wonderful sign. Here’s why this lichen can be a valuable addition to your outdoor space:

  • Air quality indicator: Lichens are incredibly sensitive to air pollution, so their presence suggests clean, healthy air in your garden
  • Low-maintenance beauty: Once established, they require absolutely no care from you
  • Year-round interest: Unlike seasonal plants, lichens provide consistent visual appeal throughout the year
  • Ecosystem support: They contribute to the complex web of life in your garden’s microhabitats
  • Natural weathering: They help break down rock surfaces gradually, contributing to soil formation over time

Perfect Spots for Willey’s Rim Lichen

This lichen naturally thrives in specific garden environments:

  • Rock gardens with exposed stone surfaces
  • Xeriscapes and drought-tolerant landscapes
  • Natural stone retaining walls
  • Areas with decorative boulders or rock features
  • Pathways made from natural stone

How to Identify Willey’s Rim Lichen

Spotting Willey’s rim lichen is easier once you know what to look for:

  • Color: Gray to whitish, sometimes with slight yellowish tints
  • Texture: Crusty and firmly attached to rock surfaces
  • Shape: Circular to irregular patches with distinct raised rims
  • Size: Can range from tiny spots to patches several inches across
  • Location: Always found on exposed rock surfaces, never on soil or wood

Creating Conditions for Natural Colonization

While you can’t plant lichens in the traditional sense, you can create conditions that encourage them to establish naturally in your garden:

  • Include natural stone features like boulders, rock walls, or stone pathways
  • Ensure good air circulation around rocky areas
  • Avoid using chemical treatments near stone surfaces
  • Be patient – lichen colonization happens slowly over months or years
  • Maintain clean air quality by avoiding excessive use of pesticides or chemicals

Caring for Existing Lichen Populations

If you’re lucky enough to have Willey’s rim lichen already growing in your garden, here’s how to keep them happy:

  • Avoid cleaning or scrubbing the rock surfaces where they grow
  • Don’t apply herbicides or other chemicals near lichen colonies
  • Resist the urge to help them by adding water or fertilizer
  • Protect them from foot traffic when possible
  • Simply observe and appreciate these slow-growing marvels

The Bottom Line

Willey’s rim lichen might not be the showiest addition to your garden, but it’s certainly one of the most fascinating. These remarkable organisms bring subtle beauty, indicate healthy environmental conditions, and connect your garden to the broader ecosystem. While you can’t rush their arrival, creating the right conditions with natural stone features and maintaining good air quality will give them the best chance to colonize your space naturally.

Next time you’re walking through your garden, take a moment to appreciate any crusty, gray patches you might spot on your rocks – you could be looking at one of nature’s most successful partnerships, quietly thriving in your own backyard.

Willey’s Rim Lichen

Classification

Group

Lichen

Kingdom

Fungi - Fungi

Subkingdom
Superdivision
Division

Ascomycota - Sac fungi

Subdivision
Class

Ascomycetes

Subclass
Order

Lecanorales

Family

Lecanoraceae Körb.

Genus

Lecanora Ach. - rim lichen

Species

Lecanora willeyi Tuck. - Willey's rim lichen

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