North America Native Plant

Wart Lichen

Botanical name: Verrucaria halizoa

USDA symbol: VEHA5

Habit: lichen

Native status: Native to North America  

Synonyms: Verrucaria microspora auct. (VEMI5)   

Wart Lichen: The Tiny Garden Guardian You Never Knew You Had Ever noticed those crusty, warty patches on rocks in your garden and wondered what they are? Meet Verrucaria halizoa, commonly known as wart lichen – a fascinating organism that’s probably been quietly living in your outdoor space without you ...

Wart Lichen: The Tiny Garden Guardian You Never Knew You Had

Ever noticed those crusty, warty patches on rocks in your garden and wondered what they are? Meet Verrucaria halizoa, commonly known as wart lichen – a fascinating organism that’s probably been quietly living in your outdoor space without you even realizing it!

What Exactly Is Wart Lichen?

Before we dive deeper, let’s clear up what wart lichen actually is. Despite its name, Verrucaria halizoa isn’t a plant at all – it’s a lichen! Lichens are remarkable partnerships between fungi and algae, working together in perfect harmony. The fungus provides structure and protection, while the algae produce food through photosynthesis. It’s like nature’s ultimate roommate situation that actually works out perfectly.

Wart lichen gets its common name from its distinctive warty, crusty appearance. You might also encounter it listed under the synonym Verrucaria microspora in older references, but don’t let that confuse you – it’s the same fascinating organism.

Where Does Wart Lichen Call Home?

This native North American species has been quietly establishing itself across the continent for centuries. You’re most likely to spot it along coastal areas, where it thrives on rocky surfaces near the shore. It has a particular fondness for the salt-spray zones where few other organisms can survive.

Spotting Wart Lichen in Your Garden

Identifying wart lichen is easier than you might think once you know what to look for:

  • Forms thin, crusty patches on rocks and stone surfaces
  • Dark-colored appearance, often grayish to blackish
  • Warty, bumpy texture that gives it its common name
  • Typically found on hard, mineral-rich surfaces
  • Prefers areas with good air circulation and some moisture

Is Wart Lichen Good for Your Garden?

Here’s where things get interesting – while you can’t exactly plant wart lichen like you would a flower, its presence in your garden is actually a wonderful sign! Lichens are incredibly sensitive to air pollution, so finding them growing naturally means your garden enjoys clean, healthy air.

Think of wart lichen as nature’s air quality monitor. These remarkable organisms absorb nutrients and moisture directly from the atmosphere, making them excellent indicators of environmental health. If they’re thriving on your garden rocks, you can feel good about the air quality in your outdoor space.

Creating Lichen-Friendly Spaces

While you can’t plant wart lichen directly, you can create conditions that encourage lichens to establish naturally:

  • Include natural stone features like rock walls, boulders, or stone pathways
  • Avoid using chemical treatments near rocky areas
  • Maintain good air circulation in your garden
  • Be patient – lichens grow very slowly and establish over time

The Bigger Picture

Wart lichen might not be the showiest addition to your garden, but it represents something beautiful about native ecosystems working as they should. These tiny partnerships between fungi and algae have been quietly doing their job for millions of years, breaking down rocks, cycling nutrients, and indicating healthy environments.

Next time you’re walking through your garden and spot those warty patches on your stones, take a moment to appreciate these remarkable organisms. They’re proof that your garden is supporting the complex web of life that makes our native landscapes so resilient and wonderful.

So while you might not rush out to plant wart lichen, you can certainly celebrate its presence and create spaces where it – and countless other native organisms – can thrive naturally.

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 halizoa Leight. - 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