North America Native Plant

California Pore Lichen

Botanical name: Pertusaria californica

USDA symbol: PECA34

Habit: lichen

Native status: Native to North America  

California Pore Lichen: A Fascinating Garden Visitor You Can’t Plant Have you ever noticed those crusty, grayish patches on tree bark in your garden and wondered what they were? You might be looking at California pore lichen (Pertusaria californica), a remarkable organism that’s neither plant nor animal, but something wonderfully ...

California Pore Lichen: A Fascinating Garden Visitor You Can’t Plant

Have you ever noticed those crusty, grayish patches on tree bark in your garden and wondered what they were? You might be looking at California pore lichen (Pertusaria californica), a remarkable organism that’s neither plant nor animal, but something wonderfully in between.

What Exactly Is California Pore Lichen?

California pore lichen is a composite organism made up of a fungus and algae living together in perfect harmony. This partnership, called symbiosis, allows the lichen to survive in places where neither organism could live alone. The fungus provides structure and protection, while the algae produces food through photosynthesis – it’s like nature’s own tiny cooperative!

This native North American species gets its common name from the distinctive pore-like structures (called perithecia) that dot its surface, giving it a uniquely textured appearance that sets it apart from other lichens.

Where You’ll Find This Natural Wonder

California pore lichen calls western North America home, with populations thriving throughout California and extending into the Pacific Northwest. You’ll typically spot it growing on the bark of various trees and occasionally on rock surfaces in areas with relatively clean air.

Identifying California Pore Lichen in Your Garden

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

  • Crusty, pale gray to whitish patches on tree bark
  • Distinctive pore-like openings scattered across the surface
  • Thick, somewhat warty texture
  • Typically grows in irregular patches rather than neat circular forms
  • May appear slightly yellowish or greenish in certain lighting

Is California Pore Lichen Beneficial to Your Garden?

Absolutely! While you can’t plant or cultivate this lichen like traditional garden plants, its presence is actually a wonderful sign for your outdoor space:

  • Air quality indicator: Lichens are sensitive to air pollution, so finding them means your garden has relatively clean air
  • Ecosystem support: They provide habitat and food for tiny insects and other small creatures
  • Natural beauty: These living artworks add subtle texture and interest to tree bark
  • Minimal impact: Unlike some organisms, lichens don’t harm their host trees

Why You Can’t (And Shouldn’t Try to) Grow It

Here’s the thing about lichens – they’re not something you can pick up at the garden center or grow from seed. California pore lichen establishes itself naturally when conditions are just right, including:

  • Clean air with minimal pollution
  • Appropriate moisture levels
  • Suitable substrate (the right type of tree bark)
  • Proper light conditions

The best approach is to simply appreciate them when they appear naturally in your garden. Trying to transplant or cultivate lichens rarely works and can damage both the lichen and its host.

Creating a Lichen-Friendly Garden Environment

While you can’t plant California pore lichen directly, you can encourage conditions that might attract it and other beneficial lichens:

  • Maintain healthy, diverse trees with textured bark
  • Avoid using harsh chemicals or pesticides
  • Keep your garden naturally humid with appropriate watering
  • Minimize air pollution sources around your property
  • Leave some areas of your garden less manicured

A Living Indicator of Garden Health

Think of California pore lichen as nature’s stamp of approval on your garden’s environmental health. When you spot these fascinating organisms growing naturally on your trees, take a moment to appreciate the complex biological processes happening right in your backyard. They’re a reminder that gardens are ecosystems supporting far more life than just the plants we deliberately cultivate.

So next time you’re strolling through your garden, take a closer look at those tree trunks. You might just discover you’re hosting some of nature’s most remarkable partnerships!

California 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 californica Dibben - California 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