North America Native Plant

Eggyolk Lichen

Botanical name: Candelariella athallina

USDA symbol: CAAT60

Habit: lichen

Native status: Native to North America  

Eggyolk Lichen: The Tiny Yellow Powerhouse in Your Garden Have you ever noticed tiny patches of bright yellow-green growing on rocks, concrete, or tree bark around your property? Meet the eggyolk lichen (Candelariella athallina), a fascinating organism that’s probably been quietly thriving in your garden without you even knowing it! ...

Eggyolk Lichen: The Tiny Yellow Powerhouse in Your Garden

Have you ever noticed tiny patches of bright yellow-green growing on rocks, concrete, or tree bark around your property? Meet the eggyolk lichen (Candelariella athallina), a fascinating organism that’s probably been quietly thriving in your garden without you even knowing it!

What Exactly Is Eggyolk Lichen?

Despite its name suggesting it’s a plant, eggyolk lichen is actually a remarkable partnership between a fungus and an algae living together in perfect harmony. This crustose lichen forms thin, crusty patches that literally become part of whatever surface they’re growing on – you can’t peel them off like you might with other types of lichens.

The eggyolk lichen gets its charming common name from its distinctive bright yellow-green color that can remind you of a sunny-side-up egg yolk. Scientifically known as Candelariella athallina, this little marvel is native to North America and has made itself quite at home across the continent.

Where You’ll Find This Colorful Character

Eggyolk lichen is wonderfully widespread across North America, popping up everywhere from Canada down to Mexico. It’s remarkably adaptable and can be found in both urban and natural environments, showing an impressive tolerance for air pollution that many other lichens can’t handle.

Spotting Eggyolk Lichen in Your Space

Here’s how to identify this bright little organism:

  • Look for small, scattered patches of bright yellow-green color
  • Check concrete walls, sidewalks, rocks, and tree bark
  • Notice the thin, crusty texture that seems painted on to surfaces
  • Observe that the patches are firmly attached and can’t be easily removed
  • Spot the slightly granular or powdery appearance up close

Is Eggyolk Lichen Good for Your Garden?

Absolutely! While you can’t plant or cultivate eggyolk lichen like traditional garden plants, its presence is actually a wonderful sign. This little organism contributes to your garden’s ecosystem in several important ways:

  • Adds biodiversity to your outdoor space
  • Provides food for tiny insects and other small creatures
  • Acts as a natural air quality indicator
  • Contributes to the weathering and soil formation process
  • Adds natural color and texture to hardscapes

Living Alongside Your Lichen Neighbors

The beauty of eggyolk lichen is that it requires absolutely no care from you! It thrives on neglect and will establish itself naturally on suitable surfaces. If you’re lucky enough to have it appearing in your garden, simply let it be. It won’t harm your plants, structures, or hardscaping – it’s just quietly doing its job as part of nature’s cleanup crew.

Some gardeners even consider patches of colorful lichen on stone walls or garden sculptures as natural art, adding character and a sense of age to their landscapes. The bright yellow-green color can provide an unexpected pop of color against gray concrete or brown bark.

The Bottom Line

Eggyolk lichen might not be something you can pick up at the garden center, but it’s definitely something to appreciate when it shows up naturally in your outdoor space. This hardy little organism represents the incredible diversity of life that can thrive in our gardens, often in the most unexpected places. Next time you’re walking around your property, take a moment to look for those cheerful yellow-green patches – you might just spot your own colony of eggyolk lichen adding its own special touch to your garden’s ecosystem!

Eggyolk Lichen

Classification

Group

Lichen

Kingdom

Fungi - Fungi

Subkingdom
Superdivision
Division

Ascomycota - Sac fungi

Subdivision
Class

Ascomycetes

Subclass
Order

Lecanorales

Family

Candelariaceae Hakul.

Genus

Candelariella Müll. Arg. - eggyolk lichen

Species

Candelariella athallina (Wedd.) Du Rietz - eggyolk lichen

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