North America Native Plant

Wart Lichen

Botanical name: Verrucaria rheitrophila

USDA symbol: VERH

Habit: lichen

Native status: Native to North America  

Synonyms: Verrucaria kernstockii Zschacke (VEKE)   

Wart Lichen: A Tiny Marvel You Might Miss in Your Garden Have you ever noticed tiny dark patches on rocks in natural areas and wondered what they were? Meet the wart lichen (Verrucaria rheitrophila), a fascinating organism that’s neither plant nor animal, but something wonderfully unique. While you won’t be ...

Wart Lichen: A Tiny Marvel You Might Miss in Your Garden

Have you ever noticed tiny dark patches on rocks in natural areas and wondered what they were? Meet the wart lichen (Verrucaria rheitrophila), a fascinating organism that’s neither plant nor animal, but something wonderfully unique. While you won’t be planting this little marvel in your garden beds, understanding what it is can help you appreciate the incredible diversity of life that might already be thriving in your landscape’s rocky corners.

What Exactly Is Wart Lichen?

Wart lichen belongs to that mysterious group of organisms called lichens – fascinating partnerships between fungi and algae that work together to survive in some pretty tough conditions. Think of it as nature’s ultimate roommate situation, where both partners benefit from the arrangement. The fungus provides structure and protection, while the algae produces food through photosynthesis.

Verrucaria rheitrophila, also known by its scientific synonym Verrucaria kernstockii, is native to North America and represents just one of thousands of lichen species found across our continent. These remarkable organisms have been quietly colonizing rocks and other surfaces for millions of years, long before our ancestors even thought about gardening.

Where You Might Spot This Tiny Wonder

Wart lichen is found throughout North America, particularly thriving in alpine and subalpine environments where conditions might seem harsh to us but are just perfect for these hardy survivors. You’re most likely to encounter them in mountainous regions, though they can appear in various rocky habitats across the continent.

Identifying Wart Lichen

Spotting wart lichen requires a keen eye, as these organisms are masters of blending in with their surroundings. Here’s what to look for:

  • Thin, dark crusts that seem to be painted directly onto rock surfaces
  • Small, black, wart-like fruiting bodies (hence the name!) that dot the surface
  • A texture that appears almost embedded in the rock itself
  • Preference for specific types of rock substrates

Don’t expect anything flashy or colorful – wart lichens are the strong, silent types of the lichen world, preferring understated earth tones that help them merge seamlessly with their rocky homes.

Is Wart Lichen Beneficial to Your Garden?

While you can’t cultivate wart lichen like you would your favorite perennials, discovering these organisms in your landscape is actually a wonderful sign. Lichens are excellent indicators of air quality – they’re sensitive to pollution, so their presence suggests you’ve got clean air in your area. That’s great news for both you and your plants!

Here are some benefits of having lichens around your property:

  • They indicate good environmental health
  • They contribute to the breakdown of rocks over geological time, slowly creating soil
  • They add to the biodiversity of your landscape’s ecosystem
  • They provide food for some wildlife species, though specific benefits for Verrucaria rheitrophila are not well documented

Working with Nature’s Rock Artists

Unlike your garden plants, wart lichens don’t need (or want) your help to thrive. In fact, the best thing you can do for any lichens you discover on your property is simply leave them alone. They’ve mastered the art of low-maintenance living and prefer to handle their own affairs.

If you’re lucky enough to have natural rock formations or stone features in your landscape where lichens have taken up residence, consider it a bonus feature rather than something that needs management. These tiny organisms are incredibly slow-growing and can take years or even decades to establish, so disturbing them means losing something that took nature a very long time to create.

The Bottom Line

Wart lichen might not be the showstopper you’d choose for your front yard display, but it represents something pretty amazing – life finding a way to thrive in the most unexpected places. While you can’t add it to your shopping list at the garden center, appreciating these small wonders can deepen your connection to the natural world right in your own backyard.

Next time you’re walking around your property or exploring natural areas, take a moment to look closely at rock surfaces. You might just spot some wart lichen quietly doing its thing, reminding us that gardens aren’t just about what we plant, but also about recognizing and celebrating the incredible diversity of life that surrounds us every day.

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 rheitrophila Zschacke - 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