North America Native Plant

Pore Lichen

Botanical name: Pertusaria lecanina

USDA symbol: PELE15

Habit: lichen

Native status: Native to North America  

Pore Lichen: The Fascinating Crusty Character Living on Your Trees Have you ever noticed those crusty, grayish patches on tree bark and wondered what they were? Meet the pore lichen (Pertusaria lecanina), a remarkable organism that’s been quietly decorating North American landscapes long before any of us started thinking about ...

Pore Lichen: The Fascinating Crusty Character Living on Your Trees

Have you ever noticed those crusty, grayish patches on tree bark and wondered what they were? Meet the pore lichen (Pertusaria lecanina), a remarkable organism that’s been quietly decorating North American landscapes long before any of us started thinking about native gardening. While you can’t exactly plant this fascinating creature in your garden, understanding what it is and recognizing its presence can give you valuable insights into your local ecosystem’s health.

What Exactly Is Pore Lichen?

Pore lichen isn’t actually a plant at all – it’s something much more interesting! Lichens are composite organisms made up of a fungus and an algae (or sometimes cyanobacteria) living together in perfect harmony. 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.

Pertusaria lecanina gets its pore nickname from the distinctive small holes or pores (called ostioles) that dot its surface. These aren’t just decorative features – they’re actually the lichen’s reproductive structures, kind of like tiny chimneys releasing spores into the world.

Where You’ll Find This Crusty Character

This native North American lichen has made itself at home across much of the continent, particularly thriving in the eastern and central regions. You’ll typically spot pore lichen doing its thing on the bark of deciduous trees, occasionally setting up shop on rocks when the mood strikes.

Is Pore Lichen Good for Your Garden?

While you can’t cultivate pore lichen (trust us, people have tried!), its presence in your landscape is actually fantastic news. Here’s why you should be happy to see these crusty patches:

  • Air quality indicator: Lichens are incredibly sensitive to air pollution, so their presence means your local air quality is pretty good
  • Ecosystem health sign: A diverse lichen community indicates a healthy, balanced environment
  • No harm to trees: Despite growing on bark, lichens don’t damage their host trees – they’re just hitchhiking
  • Wildlife value: Some birds use lichen fragments for nest-building materials

How to Identify Pore Lichen

Spotting Pertusaria lecanina is easier than you might think once you know what to look for:

  • Appearance: Crusty, thick patches that are gray to whitish in color
  • Texture: Rough and warty, often described as looking like dried oatmeal (but please don’t eat it!)
  • Key feature: Those distinctive small pores scattered across the surface
  • Location: Usually found on the bark of hardwood trees, particularly oak, maple, and hickory
  • Size: Patches can range from a few inches to over a foot across

What This Means for Your Native Garden

Finding pore lichen in your landscape is like getting a gold star from nature. It tells you that your garden environment is clean and healthy enough to support these sensitive organisms. While you can’t encourage lichen growth directly, you can create conditions that support the overall ecosystem health that lichens indicate:

  • Avoid using chemical pesticides and fertilizers near trees
  • Maintain mature trees that provide stable surfaces for lichen colonization
  • Keep air quality in mind when making landscaping decisions
  • Appreciate the natural processes happening in your yard

The Bottom Line

Pore lichen might not be the showiest addition to your native plant knowledge, but it’s definitely one of the most telling. These humble, crusty organisms serve as nature’s own environmental report card, letting you know that your local ecosystem is functioning well. So the next time you’re out examining your trees, take a moment to appreciate these fascinating partnerships between fungus and algae – they’re working hard to keep your local environment in check, one crusty patch at a time.

Remember, healthy lichens mean healthy air, and healthy air means a thriving environment for all your carefully chosen native plants. It’s all connected in the beautiful web of ecological relationships that make native gardening so rewarding!

Pore Lichen

Classification

Group

Lichen

Kingdom

Fungi - Fungi

Subkingdom
Superdivision
Division

Ascomycota - Sac fungi

Subdivision
Class

Ascomycetes

Subclass
Order

Lecanorales

Family

Pertusariaceae Körb.

Genus

Pertusaria DC. - pore lichen

Species

Pertusaria lecanina Tuck. - pore lichen

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