North America Native Plant

Dotted Lichen

Botanical name: Bacidia pallens

USDA symbol: BAPA4

Habit: lichen

Native status: Native to North America  

Dotted Lichen: The Quiet Garden Guardian You Never Knew You Had Have you ever noticed those pale, crusty patches decorating the bark of your favorite oak tree or spreading across that old garden stone wall? Meet Bacidia pallens, better known as dotted lichen – a fascinating organism that’s probably already ...

Dotted Lichen: The Quiet Garden Guardian You Never Knew You Had

Have you ever noticed those pale, crusty patches decorating the bark of your favorite oak tree or spreading across that old garden stone wall? Meet Bacidia pallens, better known as dotted lichen – a fascinating organism that’s probably already living in your landscape without you even realizing it.

What Exactly Is Dotted Lichen?

Before we dive deeper, let’s clear up a common misconception: dotted lichen isn’t actually a plant at all! It’s a remarkable partnership between a fungus and an algae (or sometimes cyanobacteria) living together in perfect harmony. This symbiotic relationship creates what we see as lichen – in this case, thin, pale gray to whitish crusty patches that seem to paint themselves across tree bark and rock surfaces.

The scientific name Bacidia pallens might sound intimidating, but think of it as nature’s own living art installation that requires absolutely no maintenance from you.

Where You’ll Find This Silent Partner

Dotted lichen is native to North America and can be found across temperate regions of the continent. It’s quite the traveler, showing up from coast to coast wherever conditions are just right.

Is Dotted Lichen Good for Your Garden?

Here’s the really cool part – if you spot dotted lichen thriving in your garden, give yourself a pat on the back! This little organism is actually an indicator species, meaning its presence tells you something important about your local environment. Specifically, it’s a sign that your air quality is pretty darn good.

Lichens like Bacidia pallens are incredibly sensitive to air pollution, so they only stick around where the air is clean. Think of them as nature’s own air quality monitors, working 24/7 for free.

Spotting Dotted Lichen in Your Landscape

Keep your eyes peeled for these telltale signs:

  • Thin, crusty patches that look almost painted onto surfaces
  • Pale gray to whitish coloration
  • Preference for tree bark, especially older trees with textured bark
  • Also found on rocks, stone walls, and occasionally wooden structures
  • Forms irregular patches rather than neat, circular shapes

The Garden Role You Never Expected

While you can’t exactly plant dotted lichen (more on that in a moment), it plays some subtle but valuable roles in your garden ecosystem:

  • Adds natural texture and visual interest to tree bark and stone features
  • Helps retain moisture on bark surfaces
  • Contributes to the overall biodiversity of your garden
  • Serves as a natural indicator of environmental health

Why You Can’t Just Pop It in a Shopping Cart

Here’s where dotted lichen differs dramatically from your typical garden center finds – you simply cannot grow, plant, or cultivate it. Lichens are wild creatures that appear when and where they choose, based on a complex set of environmental factors including air quality, humidity, substrate type, and local climate conditions.

Think of lichens as the ultimate free-spirits of the natural world. They’ll show up in your garden if conditions are right, and there’s really nothing you need to do except maintain a healthy, unpolluted environment.

Creating Lichen-Friendly Conditions

While you can’t plant dotted lichen, you can create conditions that might encourage its natural establishment:

  • Maintain mature trees with interesting bark textures
  • Keep natural stone features in your landscape
  • Avoid using harsh chemicals or pesticides that might impact air quality
  • Allow some areas of your garden to remain relatively undisturbed
  • Consider your garden’s overall environmental health

The Bottom Line

Dotted lichen might not be the showiest addition to your landscape, but its presence is actually something to celebrate. It’s nature’s way of giving your garden – and your local air quality – a thumbs up. So the next time you spot those pale, crusty patches on your trees or garden stones, take a moment to appreciate this quiet guardian that’s been silently monitoring your garden’s environmental health all along.

Remember, the best gardens aren’t just about what we plant – they’re about creating spaces where all kinds of life can thrive naturally. And sometimes, that includes the humble, hardworking organisms we never thought to notice.

Dotted Lichen

Classification

Group

Lichen

Kingdom

Fungi - Fungi

Subkingdom
Superdivision
Division

Ascomycota - Sac fungi

Subdivision
Class

Ascomycetes

Subclass
Order

Lecanorales

Family

Bacidiaceae Walt. Watson

Genus

Bacidia De Not. - dotted lichen

Species

Bacidia pallens (Kullhem) Zahlbr. - dotted lichen

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