North America Native Plant

Wart Lichen

Botanical name: Verrucaria subglaucina de

USDA symbol: VESU2

Habit: lichen

Native status: Native to North America  

Wart Lichen: A Tiny but Important Garden Resident Have you ever noticed small, crusty patches on rocks or tree bark in your garden and wondered what they were? You might be looking at a lichen like Verrucaria subglaucina de, commonly known as wart lichen. While you probably didn’t plant it ...

Wart Lichen: A Tiny but Important Garden Resident

Have you ever noticed small, crusty patches on rocks or tree bark in your garden and wondered what they were? You might be looking at a lichen like Verrucaria subglaucina de, commonly known as wart lichen. While you probably didn’t plant it there yourself, this tiny organism could be quietly contributing to your garden’s ecosystem in ways you never imagined.

What Exactly Is Wart Lichen?

Wart lichen isn’t actually a plant at all – it’s a fascinating partnership between a fungus and algae (or sometimes cyanobacteria) living together in perfect harmony. This botanical odd couple creates those small, warty-looking crusts you might spot on rocks, concrete, or tree bark around your property.

The name wart lichen comes from its bumpy, raised appearance that resembles tiny warts dotting whatever surface it calls home. Don’t worry though – unlike actual warts, these little bumps are completely harmless and actually beneficial!

Where You’ll Find This Native Species

Wart lichen is native to North America, making it a legitimate part of our continent’s natural heritage. While specific distribution details for this particular species are limited, lichens in the Verrucaria genus are typically found across various regions of North America.

Is Wart Lichen Good for Your Garden?

Absolutely! While you can’t exactly plant wart lichen (it arrives on its own timeline), having it in your garden is actually a wonderful sign. Here’s why you should welcome these tiny residents:

  • They’re excellent air quality indicators – lichens are sensitive to pollution, so their presence suggests your garden has clean air
  • They help break down rock and concrete surfaces, slowly contributing to soil formation over time
  • They provide food for various small insects and other tiny creatures
  • They add subtle texture and interest to otherwise plain surfaces
  • They require zero maintenance from you – they’re the ultimate low-maintenance garden residents

How to Identify Wart Lichen

Spotting wart lichen is easier once you know what to look for:

  • Look for small, crusty patches that appear bumpy or warty
  • They’re typically grayish, though color can vary depending on moisture and age
  • They grow flat against their surface (rocks, concrete, bark)
  • The warts are actually tiny reproductive structures
  • They’re usually quite small – often just a few inches across

Creating a Lichen-Friendly Environment

While you can’t plant wart lichen directly, you can encourage lichens to find your garden appealing:

  • Avoid using pesticides and chemicals that could harm these sensitive organisms
  • Leave some natural stone surfaces uncleared
  • Don’t power-wash every surface – lichens need time to establish
  • Maintain good air quality around your property
  • Be patient – lichens grow very slowly but are worth the wait

The Bottom Line

Wart lichen might not be the showiest addition to your garden, but it’s definitely one of the most interesting. These quiet little partnerships between fungus and algae are working behind the scenes to indicate good air quality, provide food for small creatures, and add their own subtle beauty to your outdoor spaces.

Next time you spot those small, crusty patches around your garden, take a moment to appreciate these remarkable organisms. They’re proof that some of the most important garden residents are the ones you never have to water, fertilize, or worry about – they’re just there, doing their thing, making your garden a more complete ecosystem.

Wart Lichen

Classification

Group

Lichen

Kingdom

Fungi - Fungi

Subkingdom
Superdivision
Division

Ascomycota - Sac fungi

Subdivision
Class

Ascomycetes

Subclass
Order

Verrucariales

Family

Verrucariaceae Eschw.

Genus

Verrucaria Schrad. - wart lichen

Species

Verrucaria subglaucina de Lesd. - wart lichen

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