North America Native Plant

Anisomeridium Lichen

Botanical name: Anisomeridium carinthiacum

USDA symbol: ANCA34

Habit: lichen

Native status: Native to North America  

Synonyms: Arthopyrenia carinthiaca J. Steiner (ARCA39)  ⚘  Arthopyrenia dimidiata Fink (ARDI23)  ⚘  Ditremis carinthiaca (J. Steiner) R.C. Harris (DICA32)   

Anisomeridium Lichen: A Subtle Sign of a Healthy Garden Ecosystem If you’ve ever noticed dark, crusty patches on the bark of your trees and wondered what they were, you might have been looking at anisomeridium lichen (Anisomeridium carinthiacum). This understated but important organism is more than just a curious bark ...

Anisomeridium Lichen: A Subtle Sign of a Healthy Garden Ecosystem

If you’ve ever noticed dark, crusty patches on the bark of your trees and wondered what they were, you might have been looking at anisomeridium lichen (Anisomeridium carinthiacum). This understated but important organism is more than just a curious bark decoration – it’s actually a fascinating partnership between fungi and algae that serves as a living air quality monitor for your garden.

What Exactly Is Anisomeridium Lichen?

Unlike the plants we typically think of when gardening, anisomeridium lichen isn’t a plant at all. It’s what scientists call a composite organism – essentially a successful partnership between a fungus and algae that have decided to live together. The fungus provides structure and protection, while the algae handles the food production through photosynthesis. It’s nature’s version of the perfect roommate situation!

This particular lichen is native to North America and has been quietly living on tree bark across the continent for countless years. You might also see it referred to by its former scientific names, including Arthopyrenia carinthiaca or Ditremis carinthiaca, if you’re diving into older botanical references.

Where You’ll Find This Bark-Loving Lichen

Anisomeridium lichen calls eastern and central North America home, where it makes its living on the bark of deciduous trees. It’s particularly fond of mature trees in woodland settings, where it can enjoy the dappled light and stable humidity levels it craves.

How to Spot Anisomeridium Lichen

Identifying this lichen requires a bit of detective work, as it’s quite subtle in appearance:

  • Look for thin, dark crusts that seem to be growing directly from tree bark
  • The surface appears relatively smooth but may have tiny, dark bumps (these are the fruiting bodies)
  • It typically appears grayish-black to black in color
  • Unlike some flashier lichens, it doesn’t have leafy or branching structures – it’s firmly attached to its bark home
  • You’ll most commonly find it in shaded to partially shaded areas on mature deciduous trees

Is It Good for Your Garden?

Here’s where things get exciting: anisomeridium lichen is actually a fantastic indicator that your garden ecosystem is healthy! Lichens are notoriously sensitive to air pollution, so their presence suggests you’ve got good air quality in your outdoor space. Think of them as nature’s canaries in the coal mine, but in a good way.

While this lichen won’t attract pollinators (it doesn’t produce flowers), it does contribute to the overall biodiversity of your garden. It’s part of the complex web of organisms that make up a healthy woodland ecosystem, and some small insects and other tiny creatures may use it for shelter or food.

Creating Lichen-Friendly Conditions

You can’t exactly plant anisomeridium lichen like you would a tomato or rose bush. Instead, it appears naturally when conditions are right. If you want to encourage lichens in your garden, focus on:

  • Maintaining good air quality (avoid excessive use of chemicals or positioning near pollution sources)
  • Preserving mature trees, especially native deciduous species
  • Creating areas with partial shade and stable humidity
  • Avoiding excessive cleaning or scraping of tree bark
  • Being patient – lichens grow very slowly and may take years to establish

A Living Testament to Garden Health

While anisomeridium lichen might not be the showiest resident of your garden, its quiet presence speaks volumes about the health of your outdoor ecosystem. In our increasingly polluted world, any lichen growing happily in your garden is worth celebrating. It’s proof that you’re providing a clean, stable environment where these ancient partnerships can thrive.

So the next time you spot those dark, crusty patches on your tree bark, take a moment to appreciate them. You’re looking at one of nature’s most successful collaborations – and a sign that your garden is providing a healthy home for all sorts of fascinating life forms, both big and small.

Anisomeridium Lichen

Classification

Group

Lichen

Kingdom

Fungi - Fungi

Subkingdom
Superdivision
Division

Ascomycota - Sac fungi

Subdivision
Class

Ascomycetes

Subclass
Order

Dothideales

Family

Monoblastiaceae Walt. Watson

Genus

Anisomeridium (Müll. Arg.) M. Choisy - anisomeridium lichen

Species

Anisomeridium carinthiacum (J. Steiner) R.C. Harris - anisomeridium lichen

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