North America Native Plant

Dotted Lichen

Botanical name: Bacidia trachona

USDA symbol: BATR3

Habit: lichen

Native status: Native to North America  

Synonyms: Bacidia coprodes (Körb.) Lettau (BACO6)   

Dotted Lichen: A Tiny Treasure Hiding in Plain Sight Have you ever noticed tiny, crusty patches dotting the bark of trees in your garden? You might be looking at dotted lichen (Bacidia trachona), a fascinating organism that’s part of North America’s natural heritage. While you can’t exactly plant this little ...

Dotted Lichen: A Tiny Treasure Hiding in Plain Sight

Have you ever noticed tiny, crusty patches dotting the bark of trees in your garden? You might be looking at dotted lichen (Bacidia trachona), a fascinating organism that’s part of North America’s natural heritage. While you can’t exactly plant this little wonder in your garden, understanding what it is and why it matters can deepen your appreciation for the hidden ecosystems thriving right under your nose.

What Exactly Is Dotted Lichen?

Before we dive deeper, let’s clear up what a lichen actually is – because it’s pretty mind-blowing! Lichens aren’t plants at all. They’re incredible partnerships between fungi and algae (or sometimes cyanobacteria) living together in perfect harmony. The fungus provides structure and protection, while the algae produces food through photosynthesis. It’s like nature’s ultimate roommate situation!

Bacidia trachona, also known by its scientific synonym Bacidia coprodes, belongs to this remarkable group of organisms. This particular lichen is native to North America and has been quietly decorating our trees for centuries.

Where You’ll Find This Natural Artist

Dotted lichen is widespread across North America, making its home on the bark of various trees. It’s particularly fond of deciduous trees and can be spotted from coast to coast in areas with relatively clean air.

Identifying Your Backyard Dotted Lichen

Spotting Bacidia trachona is like finding nature’s tiny polka dots. Here’s what to look for:

  • Small, crusty patches that appear almost painted onto tree bark
  • Grayish to pale greenish coloration
  • Distinctive dotted or speckled appearance (hence the name!)
  • Typically grows in small colonies rather than large, spreading patches
  • Most commonly found on the bark of hardwood trees

Is Dotted Lichen Good for Your Garden?

Absolutely! While you might not have invited this little guest to your garden party, dotted lichen is actually a wonderful indicator that your outdoor space is healthy. Here’s why having it around is fantastic news:

  • Air quality indicator: Lichens are sensitive to air pollution, so their presence suggests you’ve got clean air in your garden
  • Biodiversity booster: They provide food and shelter for tiny insects and other microscopic creatures
  • Natural beauty: They add subtle texture and interest to tree bark
  • Zero maintenance: They take care of themselves completely

The Growing Reality

Here’s where things get interesting – you can’t actually grow or plant dotted lichen like you would a flower or shrub. These remarkable organisms establish themselves naturally when conditions are right. They’re incredibly slow-growing and can take years to become noticeable.

If you want to encourage lichens in your garden, focus on:

  • Maintaining good air quality (avoid excessive use of chemicals)
  • Preserving mature trees that provide suitable bark surfaces
  • Being patient – lichens work on their own timeline
  • Avoiding the urge to scrub them off (they don’t harm trees!)

Living in Harmony with Your Lichen Neighbors

If you discover dotted lichen in your garden, consider yourself lucky! These tiny organisms are doing their part to create a balanced ecosystem. They don’t damage trees – they’re simply using the bark as a surface to call home.

The best thing you can do is simply appreciate them for what they are: silent partners in your garden’s ecosystem, working tirelessly to add biodiversity and natural beauty to your outdoor space. Next time you’re wandering through your garden, take a moment to appreciate these tiny marvels – they’re proof that sometimes the most incredible things come in the smallest packages!

Dotted Lichen

Classification

Group

Lichen

Kingdom

Fungi - Fungi

Subkingdom
Superdivision
Division

Ascomycota - Sac fungi

Subdivision
Class

Ascomycetes

Subclass
Order

Lecanorales

Family

Bacidiaceae Walt. Watson

Genus

Bacidia De Not. - dotted lichen

Species

Bacidia trachona (Ach.) Lettau - dotted lichen

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