North America Native Plant

Lesley’s Rimmed Lichen

Botanical name: Aspicilia lesleyana

USDA symbol: ASLE24

Habit: lichen

Native status: Native to North America  

Synonyms: Lecanora lesleyana (Darbish.) Paulson (LELE21)   

Lesley’s Rimmed Lichen: A Fascinating Rock-Dwelling Organism in Your Garden Have you ever noticed crusty, grayish patches decorating the rocks in your garden or local landscape? You might be looking at Lesley’s rimmed lichen (Aspicilia lesleyana), a fascinating organism that’s neither plant nor animal, but something wonderfully unique. This native ...

Lesley’s Rimmed Lichen: A Fascinating Rock-Dwelling Organism in Your Garden

Have you ever noticed crusty, grayish patches decorating the rocks in your garden or local landscape? You might be looking at Lesley’s rimmed lichen (Aspicilia lesleyana), a fascinating organism that’s neither plant nor animal, but something wonderfully unique. This native North American species adds subtle beauty to stone surfaces while playing an important ecological role that many gardeners overlook.

What Exactly Is Lesley’s Rimmed Lichen?

Aspicilia lesleyana belongs to the remarkable world of lichens – composite organisms formed by a partnership between fungi and algae. Think of it as nature’s ultimate roommate situation, where two very different organisms team up to create something neither could achieve alone. The fungal partner provides structure and protection, while the algae partner produces food through photosynthesis.

This particular lichen is also known by its scientific synonym Lecanora lesleyana, though Aspicilia lesleyana is the currently accepted name. It’s part of a diverse group of rock-dwelling lichens that have mastered the art of thriving in seemingly impossible conditions.

Geographic Distribution and Habitat

Lesley’s rimmed lichen calls western North America home, particularly flourishing in the arid and semi-arid regions where many other organisms struggle to survive. You’ll typically find it colonizing rock surfaces in areas with good air circulation and minimal moisture retention.

How to Identify Lesley’s Rimmed Lichen

Spotting this lichen is like finding nature’s graffiti on rocks – but much more sophisticated! Here’s what to look for:

  • Crusty, patch-like growth that appears firmly attached to rock surfaces
  • Whitish to pale gray coloration, sometimes with a slight yellowish tinge
  • Distinctive raised rims around the reproductive structures (called apothecia)
  • Typically forms irregular patches ranging from small spots to larger colonies
  • Texture that’s neither fuzzy nor leafy, but rather like a thin, crusty coating

Is Lesley’s Rimmed Lichen Beneficial to Your Garden?

While you can’t exactly plant or cultivate Lesley’s rimmed lichen like you would a flower or shrub, its presence in your garden is actually a wonderful sign! Here’s why this little rock-dweller deserves your appreciation:

Environmental Indicators

Lichens are incredibly sensitive to air quality, making them living air pollution detectors. If you spot healthy lichen populations in your area, it’s a good indication that your local air quality is relatively clean.

Ecological Contributions

While lichens don’t provide nectar or pollen like flowering plants, they do contribute to the ecosystem in subtle ways:

  • Provide microhabitats for tiny insects and other small creatures
  • Help break down rock surfaces over time, contributing to soil formation
  • May serve as nesting material for some birds and insects
  • Add to the overall biodiversity of your garden ecosystem

Creating Lichen-Friendly Conditions

You can’t plant Lesley’s rimmed lichen, but you can create conditions that might attract it and other native lichens to your garden:

  • Include natural stone features like rock gardens, stone walls, or boulder arrangements
  • Avoid using chemical treatments on stone surfaces
  • Maintain good air circulation around rock features
  • Choose locations with appropriate light exposure – not too shaded, not too harsh
  • Be patient – lichens grow extremely slowly and may take years to establish

Living with Lichens

If you discover Lesley’s rimmed lichen on stones in your garden, consider yourself lucky! These slow-growing organisms can take decades to establish substantial colonies. Rather than trying to remove them, embrace their presence as a sign of a healthy, balanced ecosystem.

Remember, lichens are incredibly slow-growing and sensitive to disturbance. Even light scraping or pressure washing can destroy colonies that took years to develop. The best approach is simply to observe and appreciate these remarkable organisms for the natural art they create on your garden’s stone surfaces.

The Bottom Line

Lesley’s rimmed lichen might not be the showiest addition to your garden, but it’s certainly one of the most fascinating. This native North American species represents millions of years of evolutionary cooperation and adaptation. While you can’t cultivate it like traditional plants, you can appreciate its presence as a sign of environmental health and add to the incredible diversity that makes natural gardens so special.

Next time you’re wandering through your garden, take a moment to examine those crusty patches on your rocks. You might just be looking at Lesley’s rimmed lichen – a tiny testament to nature’s incredible ability to find life in the most unexpected places.

Lesley’s Rimmed Lichen

Classification

Group

Lichen

Kingdom

Fungi - Fungi

Subkingdom
Superdivision
Division

Ascomycota - Sac fungi

Subdivision
Class

Ascomycetes

Subclass
Order

Lecanorales

Family

Hymeneliaceae Körb.

Genus

Aspicilia A. Massal. - rimmed lichen

Species

Aspicilia lesleyana Darbish. - Lesley's rimmed lichen

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