Dot Lichen: The Tiny Garden Helper You Never Knew You Had
Have you ever noticed tiny dark spots scattered across the bark of your trees and wondered what they might be? Meet the dot lichen (Arthonia rhoidis), a fascinating little organism that’s probably already living in your garden—and you didn’t even know it!
What Exactly Is Dot Lichen?
Before we dive in, let’s clear up what a lichen actually is. Lichens aren’t plants in the traditional sense—they’re amazing partnerships between fungi and algae working together as one organism. The dot lichen gets its name from its appearance: tiny, dark, dot-like spots that appear on tree bark. Think of them as nature’s polka dots!
Dot lichen is native to North America, making it a natural part of our local ecosystems. You’ll find it scattered across eastern and central regions of the continent, quietly doing its thing on the bark of various trees.
Is Dot Lichen Good for Your Garden?
The short answer? Absolutely! Here’s why you should be happy to spot dot lichen in your garden:
- Air quality indicator: Lichens are like nature’s air quality monitors. Their presence suggests you have relatively clean air in your garden
- Harmless to trees: Unlike some organisms, dot lichen doesn’t damage or parasitize your trees—it just uses the bark as a place to live
- Biodiversity booster: These little organisms add to the overall biodiversity of your garden ecosystem
- Low maintenance: They require absolutely no care from you and won’t spread aggressively
How to Identify Dot Lichen
Spotting dot lichen is pretty straightforward once you know what to look for:
- Look for small, dark spots on tree bark—usually black or very dark brown
- The spots are typically round or slightly irregular in shape
- They’re quite small, often just a few millimeters across
- You’ll find them scattered across smooth to moderately textured bark
- They tend to prefer mature trees in shaded areas
Creating Lichen-Friendly Conditions
While you can’t exactly plant dot lichen (it shows up on its own when conditions are right), you can create an environment where it’s more likely to thrive:
- Maintain mature trees: Older trees with established bark provide the best habitat
- Avoid air pollution: Keep your garden as pollution-free as possible
- Provide some shade: Dot lichen prefers areas that aren’t in full, blazing sun all day
- Skip the pressure washing: Avoid aggressively cleaning tree bark where lichens might be growing
The Bottom Line
Dot lichen might be small and easy to overlook, but it’s actually a sign that your garden ecosystem is healthy and balanced. Rather than something to worry about or remove, consider it a tiny badge of honor—proof that you’re providing a welcoming environment for native organisms.
Next time you’re wandering through your garden, take a moment to look closely at your tree bark. Those little dark dots you spot might just be your new favorite garden residents!
