North America Native Plant

Dot Lichen

Botanical name: Arthonia xylographica

USDA symbol: ARXY

Habit: lichen

Native status: Native to North America  

Dot Lichen: The Tiny Garden Guest You Never Invited (But Should Welcome) Have you ever noticed tiny black dots scattered across the bark of trees in your yard? Meet the dot lichen, scientifically known as Arthonia xylographica – a fascinating little organism that’s probably been quietly calling your garden home ...

Dot Lichen: The Tiny Garden Guest You Never Invited (But Should Welcome)

Have you ever noticed tiny black dots scattered across the bark of trees in your yard? Meet the dot lichen, scientifically known as Arthonia xylographica – a fascinating little organism that’s probably been quietly calling your garden home without you even realizing it.

What Exactly Is Dot Lichen?

Before we dive in, let’s clear up a common misconception: dot lichen isn’t actually a plant at all! It’s a lichen – a remarkable partnership between a fungus and an algae that work together in perfect harmony. Think of it as nature’s original roommate success story, where both parties benefit from the arrangement.

This native North American species forms thin, grayish crusts on tree bark, decorated with tiny black fruiting bodies that look like someone sprinkled pepper across the surface. These little black dots are where the dot lichen gets its charming common name.

Where You’ll Find This Bark-Dwelling Beauty

Dot lichen is widely distributed across North America, making appearances from Canada down through the United States. It’s not picky about location – you might spot it in urban parks, suburban backyards, or deep in the forest.

How to Identify Dot Lichen

Spotting dot lichen is like being a nature detective. Here’s what to look for:

  • Thin, grayish crusty patches on tree bark
  • Tiny black dots (fruiting bodies) scattered across the surface
  • Usually found on the bark of various tree species
  • Appears flat against the bark surface, almost painted on

Is Dot Lichen Good for Your Garden?

Absolutely! While you can’t exactly plant or cultivate dot lichen (it does its own thing, thank you very much), its presence in your garden is actually a wonderful sign. Here’s why you should be thrilled to spot it:

  • Air quality indicator: Lichens are sensitive to air pollution, so their presence suggests your garden enjoys relatively clean air
  • Ecosystem health: They’re part of a healthy, balanced ecosystem
  • Harmless to trees: Despite what some people think, lichens don’t harm their host trees – they’re just hitchhiking
  • Adds biodiversity: Every little organism contributes to your garden’s ecological richness

Can You Grow Dot Lichen?

Here’s where things get interesting – you can’t really grow dot lichen in the traditional gardening sense. It’s not something you can pick up at the nursery or start from seed. These independent little organisms establish themselves naturally when conditions are right.

The best thing you can do is create an environment where lichens can thrive naturally:

  • Maintain good air quality around your property
  • Avoid using harsh chemicals or fungicides on trees
  • Keep a diverse mix of tree species in your landscape
  • Be patient – lichens grow very slowly

The Bottom Line

Dot lichen might be small and easy to overlook, but it’s a fascinating addition to your garden’s natural community. Rather than something to plant, think of it as a bonus feature that arrives when your garden ecosystem is healthy and balanced. The next time you’re wandering through your yard, take a moment to appreciate these tiny, spotted passengers riding along on your trees – they’re silent indicators that your little corner of the world is doing just fine.

So welcome your dot lichen guests with open arms. They’re not just pretty in their own subtle way – they’re living proof that your garden is a healthy, thriving ecosystem worth celebrating.

Dot Lichen

Classification

Group

Lichen

Kingdom

Fungi - Fungi

Subkingdom
Superdivision
Division

Ascomycota - Sac fungi

Subdivision
Class

Ascomycetes

Subclass
Order

Arthoniales

Family

Arthoniaceae Rchb.

Genus

Arthonia Ach. - dot lichen

Species

Arthonia xylographica Nyl. - dot lichen

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