North America Native Plant

Matted Lichen

Botanical name: Pannaria mariana

USDA symbol: PAMA18

Habit: lichen

Native status: Native to North America  

Matted Lichen: A Natural Air Quality Indicator in Your Garden Have you ever noticed grayish-green patches growing on tree bark in your yard and wondered what they were? You might be looking at matted lichen (Pannaria mariana), a fascinating organism that’s actually doing your garden a favor by indicating clean, ...

Matted Lichen: A Natural Air Quality Indicator in Your Garden

Have you ever noticed grayish-green patches growing on tree bark in your yard and wondered what they were? You might be looking at matted lichen (Pannaria mariana), a fascinating organism that’s actually doing your garden a favor by indicating clean, healthy air quality.

What Exactly Is Matted Lichen?

Despite its name suggesting it’s a plant, matted lichen is actually a unique partnership between fungi and algae working together as one organism. This collaboration creates those crusty, mat-like patches you see on tree bark and occasionally on rocks. The fungi provides structure and protection, while the algae produces food through photosynthesis – it’s nature’s perfect roommate situation!

Where You’ll Find Matted Lichen

Pannaria mariana is native to North America, particularly thriving in the eastern regions where it enjoys temperate and boreal climates. You’ll typically spot it growing on the bark of deciduous and coniferous trees, forming those characteristic grayish-green to brownish mats that give it its common name.

Is Matted Lichen Good for Your Garden?

Here’s the exciting part – matted lichen is actually a wonderful sign for your garden! These little organisms are incredibly sensitive to air pollution, so their presence means you have clean, healthy air. Think of them as nature’s air quality monitors, working for free in your backyard.

Benefits of having matted lichen around include:

  • Indicates excellent air quality
  • Contributes to the natural ecosystem without harming trees
  • Provides tiny amounts of food for some wildlife
  • Adds natural texture and interest to tree bark

How to Identify Matted Lichen

Spotting Pannaria mariana is easier than you might think. Look for these characteristics:

  • Forms flat, crusty mats on tree bark
  • Grayish-green to brownish color
  • Texture resembles a thin, dried-out sponge
  • Grows directly attached to bark surface
  • Usually found on the shaded sides of trees

Can You Grow Matted Lichen?

Unlike your typical garden plants, you can’t actually plant or cultivate matted lichen. These organisms develop naturally when conditions are just right – clean air, proper moisture, and suitable surfaces. Attempting to transplant or encourage lichen growth typically doesn’t work, as they’re incredibly sensitive to environmental changes.

The best thing you can do is maintain a healthy, pollution-free environment in your garden. Avoid using harsh chemicals, maintain good air circulation, and keep your trees healthy. If matted lichen appears naturally, consider it a compliment to your garden’s ecosystem!

Living Alongside Matted Lichen

If you discover matted lichen growing on your trees, there’s no need to remove it. These organisms don’t harm trees – they’re simply using the bark as a surface to live on. In fact, removing lichen can sometimes damage the tree bark more than leaving it alone.

Remember, matted lichen is a sign of a healthy environment, so its presence should be celebrated rather than worried about. It’s nature’s way of telling you that your garden is a clean, welcoming space for wildlife and beneficial organisms alike.

Matted Lichen

Classification

Group

Lichen

Kingdom

Fungi - Fungi

Subkingdom
Superdivision
Division

Ascomycota - Sac fungi

Subdivision
Class

Ascomycetes

Subclass
Order

Lecanorales

Family

Pannariaceae Tuck.

Genus

Pannaria Delise - matted lichen

Species

Pannaria mariana (Fr.) Müll. Arg. - matted lichen

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