North America Native Plant

Myriotrema Lichen

Botanical name: Myriotrema microporum

USDA symbol: MYMI4

Habit: lichen

Native status: Native to North America  

Synonyms: Ocellularia micropora (Mont.) Müll. Arg. (OCMI3)   

Myriotrema Lichen: The Tiny Air Quality Detective in Your Garden Have you ever noticed small, coin-sized spots with tiny holes scattered across tree bark in your yard? You might be looking at myriotrema lichen (Myriotrema microporum), a fascinating organism that’s actually doing some pretty important work in your garden ecosystem! ...

Myriotrema Lichen: The Tiny Air Quality Detective in Your Garden

Have you ever noticed small, coin-sized spots with tiny holes scattered across tree bark in your yard? You might be looking at myriotrema lichen (Myriotrema microporum), a fascinating organism that’s actually doing some pretty important work in your garden ecosystem!

What Exactly Is Myriotrema Lichen?

Let’s clear up a common misconception first – lichens aren’t plants! Myriotrema microporum is actually a partnership between a fungus and algae, working together in perfect harmony. This collaboration creates what we see as a crusty, grayish growth on tree bark that looks almost like someone sprinkled tiny donuts across the surface.

This particular lichen goes by the scientific name Myriotrema microporum, though you might also see it referred to by its older name, Ocellularia micropora. It’s part of a large family of crustose lichens that form tight, crusty patches on their hosts.

Where You’ll Find This Native Beauty

Myriotrema microporum is native to North America, where it naturally occurs in temperate forest environments. You’re most likely to spot it in established woodlands and mature garden settings where trees have had time to develop the right bark conditions.

How to Identify Myriotrema Lichen

Spotting myriotrema lichen is like playing a fun game of nature’s hide and seek. Here’s what to look for:

  • Small, circular structures (called perithecia) that look like tiny craters or holes
  • Grayish to whitish crusty appearance that seems painted onto bark
  • Typically found on smooth-barked trees
  • Forms patches that can range from a few inches to several feet across
  • The surface appears slightly raised and bumpy when viewed up close

Is It Beneficial for Your Garden?

Absolutely! While you can’t exactly plant myriotrema lichen like you would a flower, its presence in your garden is actually fantastic news. Here’s why you should be happy to see it:

Think of lichens as nature’s air quality monitors. Myriotrema microporum is particularly sensitive to air pollution, so finding it in your garden means your local air quality is pretty good. It’s like having a tiny environmental scientist working for free!

This lichen also plays important ecological roles by:

  • Contributing to the overall biodiversity of your garden ecosystem
  • Providing microscopic habitat for various tiny organisms
  • Slowly contributing to soil formation as it eventually breaks down
  • Adding subtle texture and visual interest to tree bark

Can You Encourage Myriotrema Lichen?

While you can’t plant lichens like traditional garden plants, you can create conditions that make them more likely to appear naturally:

  • Maintain good air quality around your property (avoid excessive chemical sprays)
  • Preserve mature trees with smooth bark
  • Avoid pressure washing or scrubbing tree bark unnecessarily
  • Be patient – lichens grow very slowly and may take years to establish

Remember, lichens are incredibly slow-growing organisms. What looks like a small patch might actually be decades old, so treat any lichen growth with respect and avoid disturbing it unnecessarily.

The Bottom Line

Myriotrema microporum might not be the showiest addition to your garden, but it’s definitely one of the most interesting! If you’re lucky enough to have this native lichen naturally occurring in your yard, consider yourself blessed with a clean environment and a fascinating example of nature’s cooperation at work.

Next time you’re walking around your garden, take a moment to appreciate these tiny marvels. They’re proof that sometimes the most amazing things come in the smallest, most unassuming packages!

Myriotrema Lichen

Classification

Group

Lichen

Kingdom

Fungi - Fungi

Subkingdom
Superdivision
Division

Ascomycota - Sac fungi

Subdivision
Class

Ascomycetes

Subclass
Order

Graphidales

Family

Thelotremataceae Stizenb.

Genus

Myriotrema Fée - myriotrema lichen

Species

Myriotrema microporum (Mont.) Hale - myriotrema lichen

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