North America Native Plant

Orange Lichen

Botanical name: Caloplaca microthallina

USDA symbol: CAMI39

Habit: lichen

Native status: Native to North America  

Orange Lichen: The Tiny Splash of Color You Never Knew You Had Have you ever noticed small patches of vibrant orange or yellow-orange coloring on rocks, concrete, or even tree bark in your yard? You might be looking at orange lichen, scientifically known as Caloplaca microthallina – a fascinating organism ...

Orange Lichen: The Tiny Splash of Color You Never Knew You Had

Have you ever noticed small patches of vibrant orange or yellow-orange coloring on rocks, concrete, or even tree bark in your yard? You might be looking at orange lichen, scientifically known as Caloplaca microthallina – a fascinating organism that’s neither plant nor animal, but something wonderfully unique.

What Exactly Is Orange Lichen?

Orange lichen belongs to a remarkable group of organisms that are actually a partnership between fungi and algae (or sometimes bacteria). Think of it as nature’s ultimate roommate situation – the fungus provides structure and protection, while the algae produces food through photosynthesis. It’s a win-win arrangement that has been working perfectly for millions of years!

Caloplaca microthallina is native to North America, making it a natural part of our ecosystem. Unlike the plants you might typically think about for your garden, this little orange wonder doesn’t have roots, stems, or leaves. Instead, it forms a thin, crusty layer that hugs tightly to whatever surface it calls home.

Is Orange Lichen Good for Your Garden?

The short answer? Absolutely! Here’s why you should celebrate finding orange lichen in your outdoor spaces:

  • Air quality indicator: Lichens are incredibly sensitive to air pollution, so their presence suggests you have relatively clean air
  • Zero maintenance: They require absolutely no care from you – no watering, fertilizing, or pruning
  • Habitat provider: Tiny creatures use lichens for shelter and food
  • Natural beauty: They add subtle pops of color to otherwise bland surfaces
  • Erosion prevention: They help protect rock surfaces from weathering

How to Identify Orange Lichen

Spotting Caloplaca microthallina is easier than you might think once you know what to look for:

  • Color: Look for bright orange to yellow-orange patches
  • Texture: It appears as a thin, crusty coating that seems painted onto surfaces
  • Location: Check rocks, concrete walls, tombstones, or sometimes tree bark
  • Size: Individual patches are usually small, often just a few inches across
  • Pattern: May appear in circular or irregular shapes with slightly raised edges

Should You Try to Grow Orange Lichen?

Here’s where things get interesting – you can’t really plant orange lichen like you would a flower or shrub. Lichens establish themselves naturally when conditions are right, and they grow incredibly slowly. Trying to transplant or cultivate them rarely works and isn’t necessary.

Instead, the best approach is to simply appreciate and protect any orange lichen that appears naturally on your property. Avoid using harsh chemicals or pressure washing areas where lichens are growing, as these can damage or destroy these slow-growing organisms.

Living Alongside Your Lichen Neighbors

If you discover orange lichen in your yard, consider yourself lucky! These organisms can live for decades or even centuries when left undisturbed. They’re completely harmless to other plants, structures, and humans, making them the perfect low-key garden residents.

The next time you’re wandering around your outdoor space, take a moment to look for these tiny orange gems. They’re a reminder that some of nature’s most interesting residents are also the most undemanding – no green thumb required!

Orange Lichen

Classification

Group

Lichen

Kingdom

Fungi - Fungi

Subkingdom
Superdivision
Division

Ascomycota - Sac fungi

Subdivision
Class

Ascomycetes

Subclass
Order

Teloschistales

Family

Teloschistaceae Zahlbr.

Genus

Caloplaca Th. Fr. - orange lichen

Species

Caloplaca microthallina (Wedd.) Zahlbr. - orange lichen

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