North America Native Plant

Coenogonium Lichen

Botanical name: Coenogonium implexum

USDA symbol: COIM

Habit: lichen

Native status: Native to North America  

Coenogonium Lichen: A Fascinating Forest Friend You Might Already Have Have you ever noticed thin, crusty patches of greenish-gray growth on the bark of trees in your yard or local woods? You might be looking at coenogonium lichen (Coenogonium implexum), a fascinating organism that’s more complex than it first appears. ...

Coenogonium Lichen: A Fascinating Forest Friend You Might Already Have

Have you ever noticed thin, crusty patches of greenish-gray growth on the bark of trees in your yard or local woods? You might be looking at coenogonium lichen (Coenogonium implexum), a fascinating organism that’s more complex than it first appears. This native North American species is actually a partnership between fungi and algae, working together in one of nature’s most successful collaborations.

What Exactly Is Coenogonium Lichen?

Let’s clear up a common misconception first: lichens aren’t plants! Coenogonium implexum is what scientists call a composite organism, made up of a fungus and algae living together in a mutually beneficial relationship. The fungus provides structure and protection, while the algae produce food through photosynthesis. It’s like having the perfect roommate situation that’s lasted millions of years.

This particular lichen is native to North America and has been quietly decorating our forests long before we started paying attention to native gardening trends.

Where You’ll Find It

Coenogonium implexum makes its home primarily in the eastern regions of North America, thriving in areas with clean air and adequate humidity. You’ll typically spot it growing on the bark of deciduous trees, forming thin, crusty patches that blend seamlessly with the natural forest environment.

How to Identify Coenogonium Lichen

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

  • Forms thin, crusty patches directly on tree bark
  • Color ranges from greenish-gray to bluish-green
  • Texture appears smooth and somewhat glossy when moist
  • Creates irregular patches rather than distinct circular shapes
  • Prefers the bark of hardwood trees

Is It Beneficial for Your Garden?

Here’s where things get interesting! While you can’t exactly plant coenogonium lichen in your garden, its presence is actually a wonderful sign. Lichens are incredibly sensitive to air pollution, so finding them thriving on your trees is like getting a gold star for air quality. They’re nature’s own environmental report card.

This lichen also contributes to the ecosystem in subtle but important ways:

  • Helps create microhabitats for tiny insects and other small creatures
  • Contributes to the natural decomposition process
  • Adds to the biodiversity of your yard’s mini-ecosystem
  • Indicates healthy environmental conditions

Can You Encourage Its Growth?

While you can’t plant coenogonium lichen like you would a flower or shrub, you can create conditions that make your property more lichen-friendly:

  • Maintain healthy, mature trees (especially native hardwoods)
  • Avoid using harsh chemicals or pesticides that could affect air quality
  • Keep your trees healthy through proper care and watering
  • Be patient – lichens grow very slowly

A Living Partnership Worth Celebrating

The next time you’re walking through your yard or a local forest, take a moment to appreciate these remarkable organisms. Coenogonium implexum and other lichens represent some of nature’s most successful partnerships, quietly going about their business while contributing to the health and diversity of our ecosystems.

Remember, the presence of healthy lichens like this one is a sign that you’re doing something right in your garden. They’re proof that your little corner of the world is supporting the intricate web of life that makes native gardening so rewarding.

Coenogonium Lichen

Classification

Group

Lichen

Kingdom

Fungi - Fungi

Subkingdom
Superdivision
Division

Ascomycota - Sac fungi

Subdivision
Class

Ascomycetes

Subclass
Order

Gyalectales

Family

Gyalectaceae Stizenb.

Genus

Coenogonium Ehrenb. - coenogonium lichen

Species

Coenogonium implexum Nyl. - coenogonium lichen

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